Primary birth weakness. generic activity

Every woman dreams of safely bearing a child for the prescribed nine months and easily giving birth to him at the appointed time. But sometimes there are complications during childbirth, and things don't go the way you planned.

One of the most common causes of complicated childbirth is weak or insufficient labor activity, which leads to a delay in the process of childbirth and, as a result, to fetal hypoxia.

The weakness of labor activity is manifested in weak, short contractions, which slow down not only the smoothing and opening of the cervix, but also the progress of the fetus through the mother's birth canal. Weakness of tribal forces is more common in primiparous women.

Weak labor activity can be primary and secondary.

Primary weakness of labor activity

consists in the absence of normal dynamics of the opening of the uterine os, despite the fact that contractions are already underway.

The primary reason for the lack of labor dynamics may be:

Stress is one of the most important causes of weak labor activity. An unprepared woman has a fear of the upcoming birth, fear disturbs the hormonal balance. There is a violation from the fact that the hormones that stop childbirth are produced by the body in greater quantities than the hormones that accelerate childbirth. Sometimes one careless or rude word of the maternity hospital staff can become a factor that “knocks down” the hormonal balance.

Physiological features: a flat bubble that prevents the child from lowering; narrow pelvis in childbirth.

Low hemoglobin.

Endocrine and metabolic disorders.

Pathological changes in the uterus (inflammation, degenerative disorders, scar on the uterus, malformations of the uterus, uterine fibroids).

Overstretching of the uterus (polyhydramnios, multiple pregnancy, large fetus).

Age under 17 and over 30.

Weak physical activity during pregnancy.

Secondary weakness of labor activity

develops after the onset of labor, when normally started contractions at some point “fade out”.

Secondary weakness of labor activity develops less frequently than primary, and, as a rule:

It is the result of prolonged and painful contractions that lead to fatigue of the woman in labor;

Irrational use of drugs that affect the tone of the uterus. Unfortunately, in order for childbirth to go faster, doctors quite often speed them up artificially, even when it is not necessary.

In addition, childbirth, especially the first, can really take a long time, and if there is no threat of hypoxia for the fetus, it is not necessary to stimulate labor. Sometimes, to restore labor activity, it is enough for a woman in labor to calm down and rest a little.

Labor induction is a non-drug method.

The actions of the obstetrician depend, first of all, on the cause of the weakness of labor activity.

However, if prolonged labor really becomes dangerous for the child and mother, then with the weakness of labor activity, it is customary to stimulate labor.

The main non-drug method, allowing to strengthen generic activity, is amniotomy(opening of the fetal bladder), which is carried out when the cervix is ​​dilated by 2 cm or more. As a result of amniotomy, labor activity often intensifies, and the woman in labor copes on her own, without the introduction of drugs.

Labor induction is a medical method.

If the amniotomy does not have the desired effect, then medications are used in maternity hospitals:

1. drug sleep, during which the woman in labor restores the strength and energy resources of the uterus. After waking up, on average after 2 hours, in some women in labor, labor activity intensifies. Medication sleep occurs after the introduction of drugs from the group of narcotic analgesics, which should be done only after consulting an anesthesiologist and only in cases where the side effects from the fetus are less significant than the risk of delaying childbirth for the child.

2. Stimulation with uterotonics. The most common uterotonics are oxytocin and prostaglandins. The drugs are administered intravenously through a dropper, with a careful dosage. The condition of the fetus is necessarily monitored using a heart monitor.

Disadvantages of stimulants

As a rule, their use clearly requires the use of antispasmodics, analgesics, or epidural anesthesia. This is due to the fact that a sharp increase in labor activity often increases the pain in a woman in labor. Therefore, it is clear that labor-stimulating therapy should be used only for medical reasons, when the harm from its use is lower than the harm from prolonged labor.

C-section

If the use of drugs that accelerate labor and enhance labor activity does not work, and the fetus suffers from hypoxia, an emergency caesarean section may be chosen.

Prevention of weak labor activity.

Preventive measures to prevent weakness of labor activity include, first of all:

1. Attendance by a woman of special preparatory courses, in which the woman in labor learns what is happening to her and the child, and what she needs to do in order for the birth to be successful. The expectant mother should be ready to actively participate in the birth process, should have the right to vote in decision-making and the use of non-pharmacological methods of pain relief and stimulation of the birth process. It is known that among unprepared women in labor, weakness of labor activity occurs in 65%, and women in labor who attended childbirth preparation courses or schools for future parents during pregnancy face this complication only in 10% of cases, and they, as a rule, are due to truly objective reasons.

2. Find a hospital and a doctor you trust who is not inclined to perform unnecessarily caesarean sections. It is important that he approves of your efforts to prepare for childbirth through the birth canal. Prepare a birth plan with your doctor to make sure you have the same priorities. If you have had a caesarean section in the past, discuss the psychological and practical preparation for childbirth.

3. Consider having another helper (besides your partner) who is an experienced person who shares your aspirations.

4. Take care of your health (eat well, exercise, manage stress, avoid alcohol and tobacco) and you'll be in the best possible shape for childbirth.

5. As a prevention of weakness of labor, from 36 weeks of pregnancy, pregnant women are advised to take vitamins that increase the energy potential of the uterus (vitamin B6, folic acid, ascorbic acid).

Easy childbirth!

Edition of the Voronezh Family Portal

The content of the article

Weak labor activity, which is one of the most frequent and severe complications of the contractile function of the uterus, entails a large number of pathological conditions of the mother and fetus. According to our data, out of 30,554 cases of childbirth in urban obstetric institutions, the weakness of labor activity occurred in 2253 women in labor, which is 7.37%. The proportion of primiparas is 84%, multiparous - 16% (second births - 11.4%, third - 2%, fourth and more - 0.6%).
Clinicians distinguish two main forms of violations of the contractile function of the uterus during childbirth: weakness of labor activity and excessively violent labor activity. Moreover, in terms of the frequency of occurrence and the number of violations of the state of the mother and fetus, the weakness of labor activity is many times greater than the violent labor activity, which usually occurs in multiparous women.
There are primary weakness of contractions, secondary weakness of contractions and attempts, convulsive and segmental contractions. Excessively violent labor activity, in which the duration of labor with a full-term fetus is 3-4 hours, is called rapid labor.
The primary weakness of labor activity is manifested by contractions of weak strength, a violation of their rhythm and duration from the very beginning of their appearance and over a longer period of time. For secondary weakness of labor activity, the appearance of the same changes in uterine contraction at the end of the first or second stage of labor is characteristic. A variety of weakness of labor activity are convulsive and segmental contractions. The convulsive nature is manifested by prolonged, for more than 1.5-2 minutes, contraction of the uterus. During segmental contractions, not the entire uterus contracts, but its individual segments. Such contractions of individual segments of the uterus occur almost continuously, and their effect is negligible or extremely small.
The weakness of labor activity in a significant number of women in labor is preceded by a pathology of the condition of the membranes of the amniotic sac. 30.7% of women in labor had premature and 29.8% early discharge of water. There is a belief that the weakness of labor and the failure of the membranes of the fetal bladder in 60.5% of women in this group have the same cause.
We do not consider the untimely discharge of water as a weakness of labor activity. Many women with this pathology of the membranes - their reduced strength - have normal spontaneous labor activity.
In 32.9% of women in labor, abortions were noted in the past (artificial - in 23.4%, spontaneous - in 9.5%). As is known, artificial termination of pregnancy can have an adverse effect on the development of subsequent pregnancy and childbirth due to violations of the hormonal function of the ovaries and placenta, as well as anatomical defects in the structure of the myometrium. Spontaneous abortion is a direct consequence of the above violations, both on the basis of induced abortion, and congenital or acquired ovarian failure. Term delivery in this group of pregnant women was noted in 82%, before 38 weeks - in 0.8% and at a term of 42 weeks and more - in 17.2%.
In protracted labor, regardless of their genesis, the frequency of the use of surgical methods of delivery increases significantly. In medical hospitals in Ukraine, covering urban obstetric institutions, as well as rural central and numbered hospitals, operative methods of delivery in 1971 were used in 29.15 cases per 1000 births. The most common operation is vacuum extraction of the fetus - 16.01 per 1000 births, followed by caesarean section - 8.2, obstetric forceps - 3.54, removal of the fetus by the leg - 1.5 and fruit-destroying operations - 1.3.
The weakness of labor and the pathological conditions of the mother and fetus that accompany it are the reason for the use of the operative methods of delivery described above (252 per 1000 births). Moreover, vacuum extraction was performed in 142 cases per 1000 births, caesarean section - in 15, obstetric forceps - in 38, skin-head forceps - in 28, fruit-destroying operations - in 15 and extraction of the fetus by the leg - in 14 per 1000 births.
The prolonged course of labor increases the possibility of developing postpartum infection, which is observed 6 times more often than during normal childbirth, provided that a complex of preventive antibiotic therapy is carried out.
Labor anomalies are one of the leading causes of perinatal morbidity and mortality.
Of the total number of women in labor with weakness of labor, 34.7% experience pathological blood loss (over 400 ml) during childbirth or the early postpartum period. This pathology is the leading cause of maternal mortality and greatly complicates the course of a birth infection. All this points to the great practical importance of this problem.

Causes of labor activity

Despite the huge flow of information on the treatment of labor weakness and attempts to explain the mechanism of development of this pathology, this problem remains the least studied among other major problems of modern obstetrics.
The use of empirically substantiated methods of treating this pathology, the development of which is based on various mechanisms of dysregulation of myometrial cell contraction, often leads to unsatisfactory results and new searches for more effective means.
After the discovery of the mediator function of acetylcholine as a mediator of the transmission of nerve excitation to the effector organ, this concept was used to explain the mechanism of the development and course of childbirth. A.P. Nikolaev showed that in the blood of women in labor, amniotic fluid and cerebrospinal fluid, the mediator of nervous excitation, acetylcholine, circulates in a free form. The author suggested that the latter has an effect on the excitation of muscle cells and stimulates contraction. The release of acetylcholine into the blood, according to the author, is a consequence of the occurrence of excitation in various parts of the autonomic nervous system and the cerebral cortex.
A.P. Nikolaev and a large number of his followers believed that an increase in blood cholinesterase activity is the cause of the destruction of acetylcholine freely circulating in the blood and the development of motor inertia of the uterus. In the experiment, it was shown that acetylcholine enhances the contraction of the uterine horns of sexually mature rabbits in vitro. However, the use of acetylcholine preparations for the treatment of weakness of labor activity in the clinic turned out to be ineffective. Subsequently, it was proved that acetylcholine circulating in the blood does not have a direct effect on the spontaneously excitable system of the uterus during childbirth. The mediator acetylcholine is synthesized in nerve cells, nerve fibers and synapses. Being in vesicles, it is protected from destruction. Cell contraction is accompanied by the release of acetylcholine from synaptic vesicles, which, getting into the intersynaptic gap, leads to a change in the ionic balance and potential on the membrane of the effector cells, followed by a functional response of the excitable object. The mediator acetylcholine undergoes instantaneous destruction after the onset of the effect. The cycle is repeated. The presence of a small number of nerve terminal apparatuses in the uterus identified by modern methods of investigation raises doubts about the existence of a similar mechanism of excitation to contraction of the muscle cells of this organ. If the nerve conductors in the myometrial strip are cut, the processes of self-excitation and the response to tonomomotor drugs do not disappear.
The attempt of many authors to consider the weakness of labor activity from the standpoint of dysfunction of the cerebral cortex and vegetative centers was not successful. Sufficiently convincing facts about the direct participation of the higher parts of the central nervous system in the trigger mechanism of childbirth have not been obtained. However, in ensuring optimal conditions for the course of the birth process in the whole organism, the coordination of vital functions is provided by central regulatory mechanisms, and their role is indisputable.
With the preparation of preparations of the posterior pituitary gland (pituithrin), and later oxytocin, their high specificity was found in relation not only to the enhancement of spontaneous uterine contractions in vitro and in vivo, but also to the excitation of contractions of the myometrium, which was in a state of functional rest.
In the experiment and the clinic, it was shown that the weakness of labor activity is a consequence of the high activity of blood oxytocinase, which destroys oxytocin. It has been established that with the simultaneous administration of pituitrin and estrogen in case of weakness of labor activity, the tonomotor effect of pituitrin increases. This gave reason to talk about the inhibitory effect of estrogen on oxytocypase. It unfortunately, so far no convincing data has been presented confirming the mechanism of development of the weakness of labor activity described above. Cholinesterase and blood oxytocinase may be important to reduce the level of compounds destroyed by them, however, they do not have a direct effect on the function of organs (uterus). The use of a cholinesterase inhibitor - prozerin - proved to be ineffective in the treatment of weakness of labor, despite the increase in the content of acetylcholine in the blood.
More than 40 years ago, it became known that the sex hormones estrogen and progesterone have different effects on the long-term activity of the uterus: the former enhance it, while the latter inhibit it. Their widespread practical use for the purpose of excitation and inhibition of uterine contractions has become possible only since the synthesis of these hormones. It was also found that the functional state of the uterus can be maintained for a long time after removal of the ovaries by introducing sex hormones in accordance with the menstrual cycle. With the onset of pregnancy and in the dynamics of its development, the sex hormones of the ovary (in the early period of pregnancy), and later the placenta, have a decisive influence on the normal development of the fetus and the processes that determine the function of the uterus and the reaction of the mother's body to pregnancy. Clinicians have proven that one of the main causes of miscarriage is hormonal insufficiency of the ovaries and placenta. Hormonal correction of these disorders (estrogens + progesterone) gave a positive effect in all cases of pregnancy pathology of this genesis, if the treatment was timely and sufficient. In the next 15-20 years, an intensive study of the mechanism of action on the genital organs (mainly on the uterus) of estrogens and progesterone began in the state outside of pregnancy and in the dynamics of pregnancy. Of particular interest to clinicians were studies of the mechanism of hormonal regulation of uterine function during pregnancy and childbirth. Summary data of a large number of studies in this direction are presented in the monograph Jung (1965). Estrogen hormones as substances stimulating the spontaneous excitability of the uterus began to be widely used in klipika, often in very large doses.
It has been experimentally proved that the most favorable course of biochemical reactions in the tissues of the uterus is observed if the dose of estrogen administered to stimulate the uterus is 300-400 IU / kg. Doses of estrogens that are several times higher than the physiological ones lead to disruption of energy metabolism and suppression of the excitability of the uterus to drugs with an oxytocic effect. At present, a large clinical material has been accumulated on the combined use of estrogen and oxytocin, indicating a sufficient effectiveness of the method in the primary weakness of labor.
Over the past decade, the attention of biologists and clinicians has been attracted by two new biologically active compounds - serotonin and a group of prostaglandins, which have a fairly high selective activity in terms of stimulating the motor function of the uterus. The practical use of these compounds in the clinic to stimulate and induce labor has shown their high efficiency.
It must be assumed that in order to ensure the normal contractile function of the uterus, in addition to oxytocin, other uterotonic motor compounds are also needed that accumulate in the uterus and blood of women in labor (serotonin, catecholampins, prostaglandin).

Causes of weakness of labor activity

The reasons for the weakness of labor activity are as follows.
1. Genetically determined inertia of the mechanisms for switching on the functional systems of myometrial cells, which ensure the excitability and mechanical activity of its structures.
2. Insufficiency of the hormonal function of the fetoplacental complex, which determines the inclusion of cellular structures of the myometrium in the functional activity of excitation and contraction.
3. Morphological inferiority of the organ, causing insufficiency of function and inadequacy of the reaction to the complex of hormonal stimulation of the fetoplacental complex.
4. Functional inertness of the nervous structures (brain, spinal centers, regional nerve nodes), providing optimal conditions for the function of the uterus at the time of childbirth and in the dynamics of their development.
5. Fatigue of the uterus due to a violation of the normal anatomical relationships of the fetus and the birth canal (narrowing of the pelvis, large fetus, anomalies in the insertion and position of the fetus, structural changes in the soft tissues of the birth canal).
A large number of other factors identified as possible causes of the development of weakness in labor are subordinate to the above main reasons for the development of defective contraction of the myometrium during childbirth. Let us consider in more detail the mechanism of development of the weakness of labor activity for certain groups of reasons.
We consider the birth act as an unconditioned reflex reaction of the body, which is fixed in the hereditary apparatus of the cellular structures of the uterus and other organs, providing optimal conditions for the development of the function of this organ and the physiological conditions for the life of the fetus. The inclusion of uterine muscle cells in contraction occurs as a result of a change in the direction of specific hormonal stimulation of the gene apparatus of cellular structures. The main hormone influencing the contraction of myometrial cells are estrogens, the content and activity of which by the time of delivery change significantly in the direction of creating effects for optimal excitability reactions and contraction of the myometrium. Optimal levels of circulating estrogens in the blood and their fixation by receptor proteins of hormone-dependent cells stimulate the accumulation and activity of a number of other hormones and mediators (oxytoxin, serotope, prostaglandin Fua, catecholamines, and, apparently, other unexplored compounds with a specific action). The above biologically active compounds provide separate links in a complex self-regulating system of contraction of the muscle cells of the uterus, which is clinically manifested by childbirth. The birth act takes place at the maximum activity of the functions of many organs and functional systems (cardiovascular, excretory, metabolic, endocrine, etc.). The integration of the functions of all organs and systems of the body is carried out by the nervous structures of the brain, in which the dominant of childbirth is created, facilitating interhemispheric communications and subordination of the functions of the whole organism, ensuring the physiological course of the birth act.
If by the time the period of fetal development ends, the regulatory system of myometrial cells, which affects their excitability and contraction, does not respond to impulses emanating from the placenta and fetus, labor will not occur. The progression of pregnancy will continue until conditions arise for the inclusion of these functions of myometrial cells.
In some cases, the system of excitation and contraction of myometrial cells can be activated by neuropsychic shocks, acute infection, pain shock, vibration. It must be assumed that the excessively strong stimuli described above affect the mechanisms regulating cell function through the same humoral systems that are responsible for the mechanism of excitation and contraction during the physiological course of pregnancy. Confirmation of the correctness of the above statement about the genetic nature of the primary weakness of labor is also the fact that this pathology occurs mainly in primiparous women. The first childbirth is a kind of training for the mechanism of regulation of excitation and contraction of myometrial cells; with repeated births, this pathology is observed less frequently. The use of progesterone to block the contraction of the myometrium at various stages of the development of pregnancy enhances the processes of inhibition of the mechanisms of regulation of the tonomomotor function of cells by the time the uterine development of the fetus ends. We strive for such pregnant women to carry out prenatal preparation in order to prevent labor weakness, which in most of them removes the inertness of the mechanisms for switching on the topomotor regulation of the myometrium.
In women with ovarian dysfunction, especially with dysmenorrhea and menometrorrhagia, when pregnancy occurs, we observe high excitability and contractile function of the uterus in the early and late stages of pregnancy or tonomotor inertness in childbirth.
There is reason to believe that the violation (inhibition) of the regulation of the tonomomotor function of the muscle cells of the uterus can be caused both before and during pregnancy by other non-hormonal factors that are difficult to take into account and prevent.
Along with the cause of labor weakness described above, the latter may occur as a result of hormonal, mainly estrogenic, insufficiency of the fetoplacental complex. Our experimental and clinical studies have shown that estrogens are the main hormone that creates optimal conditions for the excitability of myometrium cell membranes and causes a cell response to substances that change the contractile properties of actomyosin. Until recently, it was believed that the leading role in the manifestation of the contractile function of myometrial cells belongs to oxytocin, although the mechanism of this action remains undiscovered. There are now many studies on the important role of serotonin and prostaglandin (F2a) in myometrial cell contraction. Under certain conditions, catecholamines (mainly adrenaline) have a pronounced tonomotor effect on the muscle cells of the uterus. The question arises, which of the above biologically active compounds is primarily responsible for uterine contractions during childbirth? We believe that the uterus, given its biological role in maintaining the life of the species, should have a duplicate system of specific contraction stimulators that compensate, and sometimes act as independent factors in the absence of the main one. The regulation of uterine contraction during childbirth includes two mutually determined dynamic processes: spontaneous excitability and contraction of muscle cells and energy metabolism, which provides the necessary levels of mechanical activity of the myometrium. A large number of biologically active compounds take part in the regulation of the first and second links of the uterus function, the effective action of which on the effector organ - the uterus - is possible only if there are optimal levels of fetoplacental hormones.
Clinical and experimental studies conducted by us and other authors (Jung, 1965) give reason to believe that compounds that affect the change in excitability and contractile properties of myometrial cells potentiate each other's action, and if one of them is insufficient, they can provide long-term time physiological parameters of uterine function.
When the contractile function of the uterus is weakened during childbirth, due to insufficient levels of circulating oxytocin or a violation of its use by myometrial cells, it is possible to completely restore uterine contraction by administering serotonin and calcium after pre-saturation of the mother's body with estrogens. Our investigations have shown that by successively introducing estrogens, serotonin and calcium, it is possible to overcome the motor inertia of the uterus and induce labor activity at various stages of pregnancy. The complex of biologically active compounds - estrogens, serotonin, calcium - ensures the restoration of the physiological course of the main links of the contractile function of the uterus in case of their violation and is the basis for initiating labor pains at various stages of pregnancy. Let us consider some of the mechanisms of these influences on the myometrium.
Serotonin (5-hydroxytryptamine, 5-HT) belongs to a group of broad-spectrum substances. However, it affects the smooth muscles in a strictly specific way. It has been established that the uterus has the ability to accumulate serotonin in large quantities (N. S. Baksheev, 1970; Fahim, 1965). Parenteral administration of labeled amine is accompanied by its accumulation in the subcellular fractions of the muscle cells of the uterus, where it is protected from destruction and can be stored for a long time (Kohren, 1965). With the introduction of 5-HT into the uterine lumen, active hyperemia, tissue edema, and stimulation of mitosis of muscle cells occur, similar to the action of estrogens (Spaziani, 1963). It has been established that there is a close relationship between serotonin and neuro-endocrine regulation carried out by the hypothalamic-pituitary system, and the amine itself is, apparently, a neurohormone with an autonomous, not yet fully disclosed mechanism of action. It has been shown that 5-HT relieves fatigue of muscle cells and restores their normal function (MM Gromakovskaya, 1967).
Studying the content of serotonin in some biological media and tissues of pregnant women, we found that during pregnancy, the concentration of 5-HT in the blood and uterine tissue increases, reaching the highest values ​​in childbirth.
In order to reveal the essence of the established relationship between the function of serotonin and calcium, N. S. Baksheev rt M. D. Kursky studied the effect of amine on the distribution of Ca45 + + in the uterine tissue and its subcellular fractions. The isotope was administered to animals (rabbits) intravenously.
Under the influence of 5-HT, the accumulation of Ca45 in the uterine muscle increases by 3.8 times, however, the degree of accumulation in each subcellular fraction is different. The most rapid and maximum accumulation of Ca45 occurs in mitochondria (at the 15th minute); this level is maintained for 180 mi p. in other fractions, the intensity of Ca45 accumulation decreases after 30 and 60 minutes. These studies have established that 5-IIT is responsible for the accumulation and metabolism of calcium in the muscle tissue of the uterus, both intravenously and intracisternally.
With the weakness of labor activity in the blood, uterine muscle and amniotic medium, the content of 5-HT is significantly reduced and the loss of calcium by uterine tissues increases. We believe that the biochemical system - fetoplacental hormones, serotonin, calcium - is responsible for providing physiological indicators of the contractile function of the uterus.
If serotonin is applied to a uterine strip that does not have spontaneous electrical activity, then in most cases spontaneous peak potentials appear after the depolarizing current is turned off, which indicates a significant change in the function of cytoplasmic membranes and contractile proteins under the action of amine.
In the absence of calcium ions in the medium, there is a shift in the membrane potential towards depolarization and a rapid loss of spontaneous electrical and mechanical activity, inhibition of excitability and an increase in the permeability of the protoplasmic membranes of smooth muscle cells of the uterus for other ions, that is, there is a complete disorganization of cell functions.
The addition of serotonin to a calcium-free solution does not affect the electrical activity and excitability of muscle cells.
If a muscle strip is preliminarily treated with serotonin in Krebs solution and placed in a calcium-free medium, the membrane potential value shifts towards depolarization, but the resistance of cytoplasmic membranes does not decrease, as is the case with the action of one calcium-free solution already in the 1st minute, but remains in within 4-5 minutes. After 5-8 minutes, the magnitude of electrotonic potentials slowly decreases and excitability decreases. Based on these studies, it can be assumed that 5-HT promotes an increase in the accumulation of calcium ions in the muscle cells of pregnant animals and ensures its economical consumption in a calcium-free medium for a long time.
The contraction of the muscle cells of the uterus during childbirth is associated with significant energy costs, the nature of which during pregnancy and childbirth is different. We have found that in the dynamics of pregnancy in the uterus, biochemical and morphological restructuring of the myometrium occurs, which provides the necessary level of motor function of the uterus during childbirth. The main role in these processes belongs to the hormones of the fetoplacental complex. To prove the role of estrogenic hormones, serotonin and calcium in these processes, we conducted experimental studies. If estrogen is administered to rabbits at the end of pregnancy (300 IU / kg for 3 days), an increase in the content of high-energy phosphates (LTP, CP), a decrease in glycogen and lactate , which indicates an increase in oxidative processes in the myometrium as a necessary phase for the manifestation of the contractile function of muscle cells.
With the introduction of the same doses of estrogens to non-pregnant rabbits, the amount of actomyosin increases 3 times (from 4.12 to 12.07%), and sarcoplasmic proteins containing enzyme groups, from 35 to 56.3%. The amount of proteins of the tonic fraction (fraction T) decreases by 50% and stromin proteins by 45%.
Significant changes were found in the myometrium of pregnant women in comparison with the state outside of pregnancy.
The content of contractile fraction proteins increases by 53% by the end of pregnancy, accounting for 40% of all myofibril proteins. The amount of sarcoplasmic proteins increases and the content of stromal proteins decreases.
Our studies show that serotonin and calcium administered separately and together (without estrogens) slightly change the fractional composition of proteins. With the introduction of these biologically active substances with estrogens, the accumulation of the optimal level of sarcoplasmic and contractile proteins occurs, and the content of adenyl nucleotides changes, the composition of which approaches that in the pregnant and giving birth uterus.
The system of adenyl nucleotides is the main system of the cell, which determines its energy costs.
We have already noted above that estradiol, serotonin and calcium, administered in a certain sequence, can restore the contractile function of the uterus weakened during childbirth. Normalization of contraction is possible with the restoration of oxidative metabolism.
Energy for muscle contraction of the uterus and other muscular organs is formed in the process of oxidative phosphorylation of carbohydrates (maximum energy output - with economical consumption of the substrate) and anaerobic decomposition of carbohydrates (minimum energy output with wasteful consumption of carbohydrates). During normal labor, the energy of uterine contraction is generated mainly in the cycle of oxidative phosphorylation, with the maximum use of oxygen. If labor is not completed within 16-17 hours, oxidative phosphorylation decreases, which can be determined by the use of oxygen by the uterine muscle obtained by caesarean section or by experimental fatigue of the uterine horn of animals. With a duration of labor of 18-24 hours, oxygen consumption by the uterine muscle decreases by 7%, 29-36 hours - by 17.2%, 99-121 hours - by 39.5%. The absorption of oxygen and the binding of inorganic phosphate in biological objects are in equimolar ratios.
This process is called coupled oxidative phosphorylation. The measure of oxidative phosphorylation is the P/O ratio (the ratio of esterified inorganic phosphate to absorbed oxygen). In normal childbirth, P/O pancake to the maximum and is 2.3. With a duration of labor of 99-121 hours, this indicator decreases by more than 2 times and is 1.1.
The transition of energy formation to the uneconomical path of glycolytic metabolism of carbohydrates is accompanied by the accumulation of excess products of interstitial metabolism (lactic, pyruvic acids).
The energy metabolism of fats is also disturbed, fatty acids and other oxidized compounds accumulate, depleting the tissue and blood buffer system. The consequence of this is metabolic acidosis and even more disruption of the homeostasis of tissues and fluids.
One of the reasons for the weakness of labor activity may be the morphological inferiority of the uterus due to trauma (abortion, surgical benefits in childbirth) and inflammatory processes. The resulting structural changes in the uterus significantly reduce the sensitivity of the mechanisms of regulation of the processes of biochemical and biophysical restructuring of all structures of the myometrium during pregnancy and childbirth. In these cases, even with a normal complex of humoral stimulants of the fetoplacental complex, there are no changes in the muscle cells necessary for the unleashing and normal course of childbirth. To this group of causes, we include overstretching of the muscles of the uterus (multiple pregnancies, polyhydramnios, large fetuses), in which there is often a weakness in labor activity.
Violation of the coordination of the functions of organs and functional systems of the body of pregnant women in the direction of creating optimal conditions for the development of the fetus and organs that ensure its vital activity and birth (placenta, uterus, amniotic medium) can weaken the contraction of the myometrium. These functions are combined by the central nervous system, the disorganization of which function can, in some cases, have a negative impact on the birth act.
To the last group of causes, we include fatigue of the uterus due to significant resistance to the advancement of the fetus from the side of the bone ring of the pelvis or soft tissues of the birth canal. The process of fatigue occurs during various periods of normal labor activity. Our clinical studies have shown that 16-18 hours after the onset of normal labor activity, paroxysms of oxidative phosphorylation occur in the myometrium, indicating a decrease in the use of oxygen in bioenergetic processes and the accumulation of acids and compounds close to them (lactic, pyroviogradic, butyric acids, etc.) that change the pH of tissues and blood. If labor activity cannot be turned off with the help of medications, not only biochemical, but also morphological changes in the muscle cells of the uterus may develop in the future, followed by persistent motor inertia of the organ. The muscle of the uterus in a state of fatigue loses the ability to fix serotonin, catecholamines, calcium. The synthesis of ATP and ADP is disrupted, glycogen stores are rapidly decreasing. With this pathology, it is necessary to prescribe medication rest (sleep) for 6-8 hours. If necessary, labor is stimulated according to the method described below.

Clinical forms of weakness of labor activity and methods of its treatment

The primary weakness of labor activity is manifested by weak and short contractions, which are accompanied by the opening of the cervix and the movement of the presenting part of the fetus into the underlying plane of the small pelvis. The displacement of the presenting part should occur no later than 4-5 hours from the onset of normal labor. With weakness of labor activity, the presenting part of the fetus can be in the same plane for 8-12 hours or more, which increases the swelling of the tissues of the birth canal and the presenting part. The first birth lasts an average of 16-18 hours, and repeated - 12-14 hours. If we take into account that the smoothing of the cervix in primiparas occurs on average within 4-6 hours, then the difference in the rate of opening of the cervix in primiparas and multiparas can be consider insignificant. For the full opening of the cervix, 10-12 hours of good labor activity are needed. The number of contractions from the beginning of childbirth to their end is 120-150 for most parturient women. Weak contraction of the uterus can occur due to the normal tone of muscle cells, as well as in the case of hyper- or hypotonicity. Hyper- and hypotonicity of the myometrium during childbirth can significantly reduce the effectiveness of each contraction. When establishing a diagnosis of the nature of the weakness of labor activity, it is necessary to strive to determine the tone of the body of the uterus, the state of which can be influenced to some extent by medications.
One of the varieties of weakness of labor activity is the segmental nature of contractions, which indicates the pathology of the spread of the contraction wave.
With the normal development of the contraction, contraction of the muscles of the uterine body occurs in one of the foci (usually in the area of ​​​​the uterine horn) and spreads down at a speed of about 10 m per 1 s. Due to a number of circumstances, the focus of excitation does not extend to the muscle cells of the entire body of the uterus, but covers only part of it. At short intervals after the contraction of one zone of the uterus, a second, and sometimes a third focus of excitation occurs. Such contractions, if determined on the basis of a zonal change in the state of the myometrium, can last 1-1.5 and even 2 minutes in the absence of progress in childbirth. Discoordinated labor activity increases the energy consumption of the uterus up to its significant depletion with an extremely low effect of childbirth.
One of the forms of labor pathology is the simultaneous contraction of the muscles of the body, cervix and lower segment of the uterus. The contractions of the muscles of the uterus and the lower segment largely offset the effect of the contraction of the body of the uterus, as a result of which conditions are created for the fatigue of the working organ.
Treatment of weakness of labor activity should be preceded by the establishment of a possible cause of this condition. The primary weakness of contractions most often has genetically determined causes or depends on the insufficiency of the hormonal function of the fetoplacental complex. Often there may be a combination of these reasons.
The excitability and contractile function of the muscle cells of the uterus are influenced by oxytocin, serotonin and their combined use with estrogens and calcium, as well as a still little studied compound from the group of prostaglandins - prostaglandin F2a.

Induction of labor with oxytocin

Oxytocin is a biologically active compound with a highly specific action that enhances the contractile function of myometrial cells. It should be noted that oxytocin does not affect the myometrium, which is devoid of the influence of estrogen hormones, which not only sensitize the membrane and contractile proteins of muscle cells, but also create conditions for ensuring energy balance in a working organ. The mechanism of action of oxytocin on muscle cells has not yet been fully elucidated, however, there are data indicating a change in the ionic structure of target cell membranes to the level of the release of spontaneous action potentials. It must be assumed that oxytocin affects the transport of calcium ions in the intracellular structures of myometrial cells, without which contraction is impossible. The method of treating weakness of labor with oxytocin is as follows. 10 units oxytocin is dissolved in 350-400 ml of 5% glucose solution and injected intravenously or subcutaneously, starting with 10-15 drops per 1 minute. If in the next 4-6 minutes the contractions do not become more frequent and do not intensify, the volume of the injected solution is increased to 25-35 drops, and then the rate of inflow of the solution is regulated depending on the activity of the contractions. It should be noted that the effect of stimulation of uterine contractions by oxytocin is directly dependent on the readiness of the myometrium to respond to this hormonal stimulus. The duration of the stimulation period is 2.5-3.5 hours.
To enhance the sensitization of the uterus to oxytocin and increase the release of its own (pituitary) oxytocin and prostaglandin into the blood, as well as the accumulation of serotonin and catecholamines in the uterus, estrogens are prescribed prior to oxytocin stimulation. Estrogen is administered in ether (0.5 ml of ether per 1 ml of an oil solution of estrogen) in the amount of 300-400 units/kg of the mother's weight. Normal labor activity occurs against the background of the highest concentrations of estrogen in the blood. The highest concentration of estrogen in the blood after the introduction of an essential oil solution is observed after 3-3.5 hours, one oil solution (without ether) - after 5-5.5 hours. Oxytocin is administered 3-3.5 hours after estrogen with ether or 5.5 hours from the start of estrogen administration without ether.
The effect of stimulating labor activity is enhanced if estrogens in ether are administered 2 times in 20,000 units. (1st time - 3.5 hours before the start of oxytocin administration, 2nd time - before the administration of oxytocin), as well as with simultaneous intravenous administration of calcium chloride or calcium gluconate (10% 10 ml). On the day and on the eve of the stimulation of labor, ascorbic acid is prescribed (preferably galascorbin 1 g 3 times a day), coamide, vitamins Bi, Bis and cocarboxylase.
If after the introduction of 10 od. oxytocin, a weak labor-stimulating effect was obtained, it is not advisable to continue stimulation with quinine, pachycarpine or prozerin, since these drugs are many times less effective than oxytocin.
If the reaction of the uterus to oxytocin was sufficiently well expressed only during the administration of the drug, after its completion it is necessary to continue stimulation with pachycarpine (3% solution of 2-3 ml in 2-3 hours) or quinine hydrochloride (0.05 g of 1 powder in 30 min 4-5 times a day). The total dose of quinine, exceeding 0.7-1 g, is toxic. We noted above that dimecoline relaxes the muscles of the cervix and accelerates the opening of the latter.
Before and during the stimulation of labor, the appointment of trioxazine (400 mg 2 times a day) is shown - a tranquilizer, which also has some relaxing effect on the tissues of the cervix. When the cervix is ​​rigid, to accelerate its opening, 64-128 units should be injected into its tissue. lidase dissolved in 50-75 ml of 0.25% novocaine. It is necessary to monitor the nutrition of the mother. Other measures (laxatives, hot enemas) with drugs such as oxytocin, serotonin, or prostaglandin F2a are ineffective.

Stimulation of labor by serotonin

Serotonin, like oxytocin, is also used after the administration of estrogens in essential oil and oil solutions. 30-40 mg of serotonin-creatine phosphate is dissolved in 350-400 ml of 5% glucose solution immediately before administration. The drug is administered intravenously starting with 10-12 drops per 1 minute. After 5 minutes from the start of administration, in the absence of individual hypersensitivity of the uterus and vascular system, you can increase the amount of the drug to 20-30 drops per 1 minute. It is necessary to monitor the tone of the uterus, as well as the strength and duration of its contraction. At the time of administration of serotonin, after 30 minutes and 1 hour 30 minutes from the start of administration, calcium gluconate or calcium chloride (10 ml each) is administered intravenously.
If, as a result of stimulation with oxytocin or serotonin, childbirth did not end, after 16-18 hours from the start of stimulation, drug sleep is prescribed for at least 6-7 hours. Labor should not be stimulated twice a day, since the energy reserves of the uterus and physical strength are depleted women in labor. After rest, the vast majority of women in labor develop good spontaneous labor activity. If necessary, the stimulation is repeated. In the absence of the effect of the action of oxytocin, serotonin is used. However, often the other drug is ineffective.

Induction of labor

Premature discharge of water is an indication for the initiation of labor not earlier than 4-6 hours from the onset of rupture of the fetal bladder. During this time, some pregnant women spontaneously develop labor activity, which does not require medical correction in the future. If there are no contractions by the time indicated above, it is necessary to start initiating labor. To excite uterine contractions, we, just as with stimulation, first administer estrogens, believing that the pathology of the structure of the fetal bladder depends on the estrogen deficiency of the fetoplacental complex. Estrogens increase the excitability of the muscle cells of the uterus, increase the release of oxytocin by the pituitary gland and release from the uterus, and possibly from the placenta, prostaglandin F2 "" increase the accumulation in the uterus of serotonin, a progesterone antagonist, as well as the accumulation and synthesis of catecholamines. Estrogens and serotonin reduce the level and activity of progesterone, as a result of which its inhibitory effect on adrenergic parauterine and intrauterine nerve structures is reduced or completely removed. The adrenergic nerve approaching the uterus can form an efferent arc of the spinal reflex, as a result of which uterine contractions begin to be stimulated further by stretching (opening) of the neck. Adrenergic innervation increases the sensitivity of the myometrium to oxytocin.
Labor induction will be effective if the oxytocin test is positive. It should be noted that with a positive oxytocin test, the effectiveness of excitation of labor by serotonin significantly increases. The essence of the test is as follows.
Take 1 unit. oxytocin and diluted in 100 ml of 5% glucose solution (1 ml of solution contains 0.01 units of oxytocin). 3-5 ml of oxytocin solution (0.03-0.05 units) is slowly injected into the vein of the elbow bend. The drug reaches its maximum concentration by the 40-45th second. The second test of the readiness of the uterus for childbirth is the degree of "maturity" of the cervix for childbirth. The preparation of the cervix for childbirth consists in its shortening, softening and compliance, as a result of which the canal smoothly passes into the lower segment of the uterus. There is a thinning of the lower edge of the vaginal part of the neck, and the neck itself is located in the region of the wire axis of the pelvis. Practice shows that the above anatomical changes in the cervix correspond to a high degree of excitability of the uterus with the introduction of oxytocin and other compounds similar in effect.
The rate of administration of oxytocin and serotonin to initiate contractions should be somewhat greater than when stimulating labor. After the initial test for 4-6 minutes, the number of drops can be increased by 5-10 every 5-6 minutes and further adjusted depending on the labor activity of the uterus. If no effect is observed with the introduction of 40-50 drops per 1 minute, the rate of administration of oxytocin should not be increased. The same is true for serotonin. It should be borne in mind that there are few pregnant women with premature discharge of water and torpid inertness of the uterus. Their cervix, despite being prepared with estrogens, remains dense for several days, the tone of the uterus is low in the complete absence of spontaneous excitability and reaction to mechanical stimuli. The threat of endometritis, and sometimes the onset of endometritis, are the basis for the use of oxytocin or serotonin to induce labor. However, the full effect is missing. In this category of women, even with the simultaneous introduction of the metreirinter (in the absence of contraindications to its use), there are also no positive results, therefore, one has to resort to long-term mechanical expansion of the cervix with dilators, and then with fingers. Usually it is possible to expand the cervix by 3-5 cm in one go. After mechanical stretching of the cervix and application of skin-head forceps (with contraindications to metreyris), another round of labor induction is carried out. It is not uncommon to induce contractions that can later be stimulated by serotonin after oxytocin is administered, or vice versa. We have repeatedly been led to observe such inertia of the uterus that only with the help of mechanical methods it was possible to expand the cervix and remove the fetus.

Initiation of labor activity for medical reasons and in the event of a prolonged pregnancy

It is often very difficult to overcome the inertia of the uterus of pregnant women, especially when the pregnancy is overdue, and this requires a certain amount of time. Labor induction begins with an increase in the excitability of the uterus, which is achieved by the introduction of estrogens at 20,000-30,000 units. daily (estradiol dipropionate) in an oil solution, galascorbin 1 g 3 times a day and 10 mg serotonin intramuscularly 5 hours after hormone administration. Simultaneously with serotonin, calcium gluconate or calcium chloride is administered intravenously, 10 ml of a 10% solution. The period of prenatal preparation lasts 3-5 days, and sometimes longer. It is necessary to monitor the state of excitability of the uterus daily. In some pregnant women, after 2-3 days, arrhythmic contractions appear with a sufficiently high excitability of the organ. With a positive oxytocin test, labor induction with oxytocin or serotonin should be carried out according to the above scheme. If the contractions weaken after stopping the administration of the drug, oxytocin can be injected subcutaneously (2 units every 1.5-2 hours) or intramuscularly - 10 mg of serotonin every 2-3 hours. Pachycarpine and quinine should not be prescribed in the absence of contractions. B vitamins and coamide are prescribed during the entire period of labor induction. If after the first treatment the effect is not obtained, the second should be carried out no earlier than in 1-2 days, continuing the appointment of estrogens and other drugs according to the above scheme. Our many years of experience in the use of the above method of labor induction testifies to its consistently high efficiency and the least number of complications in the fetus.
In the absence of oxytocin and serotonin, pituitrin (10 units) can be used, but it should be administered only subcutaneously, since collapse may occur with intravenous administration. With late toxicosis, serotonin and pituitrin should not be administered.
With secondary weakness of labor activity, when labor has entered the second period, and uterine fatigue and general physical fatigue are increasing, you can use a 1% solution of sigetin, which is administered in an amount of 2-4 ml (preferably in 20 ml of 40% glucose), and then drip introduce oxytocin or serotonin and calcium gluconate. If necessary, resort to operative delivery. If secondary weakness develops at the end of the first period of labor, one of the schemes described above can be applied.
When prescribing medical sleep (rest) to a woman in labor, we use the following combinations of medications: I - trioxazine - 600 mg, etaminal sodium - 200 mg, promedol 2% - 1 ml, no-shpa - 2 ml, pipolfen - 50 mg; II - viadril G - 50 mg intravenously, trioxazine - 600 mg, sodium etaminal - 100 mg, no-shpa - 2 ml, pipolfen - 50 mg; III - sodium hydroxybutyrate (GHB) 20% - 20 ml intravenously, no-shpa - 2 ml, pipolfen - 50 mg. Etaminal sodium can be replaced with noxiron. Discoordinated contractions decrease under the influence of no-shpa, atropine, palerol, aprofen (the latter relaxes the muscles of the cervix).
The weakness of labor almost always worsens the condition of the fetus (acidosis, hypoxia, cerebral edema). Therefore, it is necessary to carry out effective prevention of fetal asphyxia simultaneously with the stimulation of labor.

They are easy and fairly painless. But in some cases, complications of labor activity develop.

What is the weakness of labor activity?

Weakness of labor activity (SRD) is a cumulative concept that includes both a weakening of the strength and frequency of contractions of the uterine muscle, and the subsequent slowdown in the opening of the uterine pharynx. Normally, with the correct development of the birth process, with each contraction, the force of uterine contraction increases, contractions become more frequent. Following the contraction, which follows the direction from the bottom of the uterus through its body to the lower segment, there is a gradual opening and smoothing of the cervix. With anomalies of labor activity, including weakness, these processes are violated.

Types of weakness of labor activity and their causes

The weakness of labor activity is divided into:

• Primary, in which contractions have insufficient strength and regularity from the very beginning of childbirth;
• Secondary, when labor begins normally, with regular and strong contractions. After a few hours, the activity of labor activity begins to fade, sometimes to a complete stop;
• Weakness of attempts is isolated in a separate item. This is a kind of weakness at the very end of childbirth, when attempts are added to the contractions, the strength of which is insufficient for the independent birth of a child.

Sometimes AD occurs for no apparent reason at the most unexpected moment. The main reasons for this diagnosis include:

1. imbalance between factors that stimulate uterine contractility (oxytocin, calcium ions, endogenous prostaglandins) and factors that inhibit it (progesterone, magnesium ions);
2. weak generic dominant, fear of a woman, psychological unpreparedness for childbirth;
3. fatigue of the woman in labor, poor nutrition, concomitant diseases (influenza, SARS, arterial hypertension);
4. the risk group for the development of this complication are pregnant women with hypothyroidism, obesity, hypogonadism, and smokers;
5. excessive stretching of the uterine wall by a large fetus, excess amniotic fluid, twins;
6. anomalies in the development of the uterus and the presence of myomatous nodes;
7. operations on the uterus in history;
8. premature birth;
9. stimulated childbirth;
10. premature rupture of amniotic fluid.

Clinic and diagnostics of RSD

Symptoms of weakness of labor activity are quite typical. To make such a diagnosis, obstetricians pay attention to the following factors:

• the duration of childbirth, their anhydrous period is especially noted, that is, the time since the rupture of the fetal bladder;
• the dynamics of the opening of the uterine pharynx, the degree of maturity of the cervix;
• the strength, regularity and duration of contractions, which in modern obstetrics is easy to fix on the CTG chart.

Therapy for this complication of childbirth depends on the cause that caused it:

1. If a woman is tired, exhausted by pain, she is offered the so-called medical sleep-rest. Currently, spinal or epidural anesthesia is used with success;
2. Additionally, solutions of glucose, B vitamins, estrogenic drugs, calcium, actovegin are administered. These infusions stimulate uterine contractility and prevent oxygen starvation of the fetus;
3. In the case of polyhydramnios with a whole fetal bladder, it is advisable to carry out an amniotomy;
4. A cleansing enema, urine output by a catheter helps well.

A certain number of medicines are used to correct weakness.

• Oxytocin, similar to a woman's own oxytocin, directly affects the contraction of the muscle fibers of the uterus. It is introduced slowly, drip. The ideal way of administration is with the help of infusion pumps with a given speed. Learn more about .
• Prostaglandins are analogues of natural mediators that stimulate labor activity. There are these drugs in different forms (gels, tablets, solutions for intravenous administration).

In case of ineffectiveness of drug therapy and persistent weakness, the diagnosis is made: "Weakness of the birth forces (primary or secondary), not amenable to drug correction." This is a direct indication for an emergency caesarean section.

In case of weakness of attempts, a caesarean section is often done late, since the fetal head has left the cavity of the bone pelvis into the birth canal. Therefore, in this situation, they resort to the old methods:

• Episio- or perineotomy - an incision in the perineum to facilitate the birth of the head;
• The imposition of obstetric forceps or a vacuum extractor on the head of the fetus. In this case, the force applied by the obstetrician compensates for a weak attempt or contraction;
• Bandage Verbova is an old, but quite effective way to help in attempts. With the help of a dense cloth thrown over the stomach, the doctor and midwife created additional pressure from the bottom of the uterus to the exit;
• The Christeller method is a technique prohibited in many countries, fraught with the loss of a license for an obstetrician. However, sometimes, when the life of a child is at stake, it is also applicable. Its essence lies in the fact that the doctor, putting pressure on the bottom of the uterus with his elbow or forearm, literally pushes the child out.

Prevention of weakness of labor activity

Measures to prevent complications in childbirth a woman should take even before pregnancy. The main ones are:

1. proper nutrition, vitamin therapy;
2. physical activity, sports, especially developing abdominal and pelvic muscles;
3. correction of all chronic diseases before pregnancy;
4. psychological preparation for childbirth, including training courses, breathing and relaxation techniques;
5. body weight control.

During pregnancy, it is important to keep fit, active, walk a lot, breathe fresh air. Pregnancy must necessarily take place under the supervision of a gynecologist, who, at the right time, will identify risk factors for RDD and prescribe treatment.

Alexandra Pechkovskaya, obstetrician-gynecologist, specially for website

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Modern obstetrics aims to make the process of childbirth as safe as possible. One of the problems that leads to complications is the weakness of labor activity - an important cause of acute fetal hypoxia. Lack of oxygen can occur with a long period of childbirth and the use of drugs that stimulate the muscle tone of the uterus.

What is the essence of the problem

The weakness of labor activity is manifested by the lack of strength and duration of contractions of the muscular layer of the uterus, an increase in the interval between. In connection with this, the smoothing of the neck, its opening slows down. Fetal advancement also occurs at a slow pace, which can cause injuries, impaired early adaptation of newborns, and perinatal lesions.

On the part of the mother, there is a high probability of operative delivery, bleeding, infectious complications in the postpartum period. The causes of violations of the contractility of the uterus are numerous, they affect all parts of the formation of childbirth.

The modern classification of the weakness of labor activity distinguishes primary and secondary forms of pathology. Primary dysfunction occurs from the very beginning of labor and continues until the birth of the fetus. With the secondary weakening of contractions occurs after a period of good labor activity.

Causes of the pathological condition

Weakness of contractions in childbirth can occur as a result of an insufficient number and low intensity of the strength of impulses that cause and maintain labor activity, the inability of the uterus to perceive and adequately respond to them, in the presence of obstacles to childbearing. Emerging causes are conventionally divided into several groups:

Obstetric related

Mismatch between the size of the pelvis of a woman and the head of the fetus, premature discharge of amniotic fluid, anatomical features of the reproductive organs, preeclampsia, multiple pregnancy, large fetus, polyhydramnios, stubbornness and immaturity of the cervix, breech presentation, anomalies of placenta attachment.

Associated with the pathology of the female reproductive system

Neuroendocrine disorders, inflammatory diseases of the uterus and appendages, operations on the internal genital organs, abortions, miscarriage, menstrual disorders, developmental anomalies, infantilism, infertility, poor outcome of previous births.

From the side of the fetus

Used drugs for weakness of labor to activate contractions:

• Prostaglandins - Prostenon, Enzaprost, Dinoprost, Prostin, Prostarmon.
• Uterotonics - Oxytocin, Synthocinone, Pitocin.

There are various schemes using only prostaglandins, uterotonics or the combined administration of these substances. Drugs are administered with strict control over the nature of contractions and fetal heartbeats, using adequate anesthesia, following the recommendations for the duration, dosage and rate of administration of uterotonics.

When observing, they carry out: tocography, cardiomonitoring of the fetal heart, vaginal examinations of the woman in labor, monitor the timely emptying of the bladder, the general condition of the woman, measure blood pressure, pulse. Contraindications to labor stimulation are:

• transferred operations on the uterus;
• discrepancy between the size of the pelvis of the woman and the presenting part;
• incorrect position of the fetus;
• signs of distress (hypoxia) of the fetus;
• preeclampsia, hypertension, bronchial asthma - for prostaglandins;
• extensor presentation of the head;
• anomalies of the mother's pelvis (for example,), the location of the placenta;
• pathology of the cervix;
• obstacles to birth;
• lack of monitoring capability.

Activation of labor can be complicated by: discoordination of labor, placental abruption, acute fetal hypoxia, excessively violent contractions, birth injuries.

Clinical recommendations for the weakness of labor activity include the use of an energy mixture of drugs with the onset, which increases the effectiveness of the treatment of labor anomalies and labor stimulation. This complex consists of 20 ml of 40% glucose solution, 2 ml of 5% ascorbic acid solution, 10 ml of 10% calcium chloride solution administered intravenously and simultaneous intramuscular injection of 10,000 units of folliculin in 1 ml of ether for anesthesia or 0.2 ml of 2% sinestrol solution . In parallel with the introduction of these drugs, prevention of intrauterine fetal hypoxia and stimulation of labor activity are carried out.

Schemes of labor stimulation

For the prevention of distress, intravenous administration of 2-4 ml of Sigetin solution in 20-40 ml of 40% glucose is used, if necessary, injections are repeated after 30-60 minutes, but not more than 5 times.

If, after three to four hours of prostaglandin administration, the neck smoothes and opens up to four centimeters, they switch to further stimulation with oxytocin. With an adequate dose of oxytocin, labor activity normalizes to 3-5 contractions in 10 minutes, with a duration of contractions of 40 seconds, there is a dynamics of cervical dilatation of 1 cm/hour.

In the absence of activation of contractions within 2 hours against the background of the introduction of oxytocin, rhodostimulation is considered inappropriate. The lack of effect from the first dose is considered an indication for a caesarean section. Stimulation is stopped when acute signs appear, which are an indication for operative delivery.

Secondary weakness of contractile activity of the uterus

The weakening of the tribal forces in the active phase of labor or with initially normal indicators is usually called the secondary weakness of labor activity. Dysfunction can develop:

• with a discrepancy between the size of the fetus and the pelvis of the mother;
• long anhydrous period;
• large fruit;
• polyhydramnios;
• incorrect insertion of the presenting part;
• as a complication of conduction anesthesia.

Pathology is more common in multiparous. Predisposing factors for the occurrence of dysfunction, as in the primary weakness of contractions.

Secondary weakness occurs after the opening of the obstetric pharynx by 6 centimeters, it is characterized by a sharp weakening, slowing down (3 or less in 10 minutes), shortening of contractions, slowing down or stopping the progress of the presenting part. Diagnosis of the condition is carried out for 2 hours based on observations of the nature of contractions, the opening of the uterine os, and the advancement of the fetus. With untimely diagnosis and inadequate management of the woman in labor, complications may develop.

Birth management

The doctor's tactics depend on the obstetric situation - the degree of opening of the uterine os, the position of the presenting part, the condition of the fetus. The best treatment in the first stage of labor is to provide medical rest with subsequent stimulation of contractions.

When opening the neck of 5-6 cm, rhodostimulation with prostaglandins is recommended; if the technique is ineffective, they switch to the combined administration of drugs within 2 hours. Taking into account the duration of labor, and the possible negative effect of oxytocin on the fetus, it is prescribed when the opening of the uterine os is 7-8 centimeters.

The dosage and rate of administration of substances are described in the table above. If the activation of contractions with oxytocin is ineffective for 1-2 hours, there are no contraindications and there are conditions for the operation, a caesarean section is performed. Indications for operative delivery are the onset of fetal hypoxia, the impossibility of completing labor through the natural birth canal.

If the secondary weakness of labor activity occurs while the presenting part is in the pelvic cavity or exiting it, labor stimulation is started immediately. Perineotomy is performed according to indications. With a prolonged period of expulsion or the onset of asphyxia of the fetus, a vacuum is applied with an extractor or obstetric forceps, with a breech presentation, extraction is performed by the pelvic end.

It is important for obstetricians to timely distinguish secondary uterine dysfunction from a clinical discrepancy between the size of the mother's pelvis and the fetal head. With an absolute discrepancy, an emergency caesarean section is performed, since childbirth through the natural birth canal is impossible.

The weakness of the contractile activity of the uterus is one of the causes of postpartum hemorrhage. In order to prevent a formidable complication, the administration of uterotonics is continued for and within an hour after its completion.

How to prevent

Prevention should begin at puberty. During puberty, the neuroendocrine system of a woman is formed. Good nutrition, moderate physical activity, a favorable emotional background have a positive effect.

In reproductive age, it is recommended to plan a pregnancy, to treat inflammatory diseases of the female genital organs, and menstrual irregularities on time. During pregnancy, it is necessary to follow the recommendations of obstetricians on nutrition, regimen and hygiene of pregnant women, to attend a school for expectant mothers to prepare for childbirth.

Of great importance is the readiness of the body for the birth of a child, especially the cervix. Laminaria, Dinoprostone are used as means for cervical ripening. In the conditions of medical institutions, training is carried out in advance among women who are at risk for the development of anomalies in labor. In the process of childbirth, in order to prevent weakness of contractions, a woman in labor needs comfortable conditions, a long presence of a partner, and an upright position.

The weakness of labor activity is characterized by insufficient strength, duration and frequency of contractions, slow smoothing of the cervix, opening it and moving the fetus through the birth canal. All these deviations can be observed, despite the correct ratio of the size of the fetus and pelvis.

Weakness of tribal forces is more common in primiparous than in multiparous.

Primary weakness of labor is a pathological condition in which contractions from the very beginning of labor are weak and ineffective. Primary weakness of labor activity may continue during the first and second periods.

Primary weakness of the birth forces usually occurs in pregnant women with uterine hypotonicity (primary hypotonic dysfunction of the uterus). Of great importance in its etiology is the insufficiency of impulses that cause, maintain and regulate the contractile activity of the uterus, as well as its inability to perceive these impulses or respond to them with a sufficiently powerful contraction of the myometrium. Along with common causes (mother's diseases, genital infantilism), the following factors are important: a decrease in the concentration of acetylcholine, oxytocin, prostaglandins, an increase in blood cholinesterase activity, deformation (coarseness, thickening, and sometimes collagenization) of argyrophilic sheaths of muscle cells.

The duration of labor with primary weakness of labor activity increases significantly, which leads to fatigue of the woman in labor. Often, untimely discharge of amniotic fluid, lengthening of the anhydrous gap, infection of the genital tract, hypoxia and fetal death are possible.

I - normal delivery, II - primary weakness of labor, III - secondary weakness of labor

The diagnosis of primary weakness of labor activity is established on the basis of an analysis of the nature and frequency of contractions, uterine tone, and the dynamics of cervical dilatation. The weakness of labor activity is evidenced by an increase in the duration of the latent phase of labor to 6 hours or more and a decrease in the rate of cervical dilatation during the active phase to 1.2 cm/h in primiparous and 1.5 cm/h in multiparous.

The partogram speaks of the lengthening of the birth act in both the first and second stages of labor (Fig. 20.1). To assess the progression of labor, it is important to analyze the comparative data of the last two or three vaginal examinations.

It is advisable to confirm the clinical diagnosis of weakness of labor activity by indicators of objective observation (cardiotocography, hysterography).

The treatment of primary weakness of labor activity consists primarily in the correct determination of the cause and the choice, in accordance with this, of differentiated methods of dealing with it. With weak labor activity, it is necessary to control the emptying of the bladder and intestines. In parturient women with polyhydramnios and the longitudinal position of the fetus, an early artificial opening of the fetal bladder is performed, provided that the cervix is ​​smoothed and the uterine os is opened by at least 2-3 cm.

With prolonged, protracted labor, fatigue of the woman in labor, she is given medical rest (sleep), if there are no emergency indications for delivery (fetal hypoxia, the threat of excessive pressing of the soft tissues of the birth canal), since the appointment of a tired woman in labor (without previous rest) can stimulate labor activity even more complicate the course of childbirth

Obstetric anesthesia (sleep-rest) should be carried out by an anesthesiologist. For this purpose, sodium hydroxybutyrate (2-4 g) is administered intravenously simultaneously with a 20-40% glucose solution. 20-30 minutes before this, premedication is carried out: intravenously 1.0 ml of a 2% solution of promedol, 1.0 ml of a 1% solution of diphenhydramine, 0.5 ml of a 0.1% solution of atropine. It should be remembered that sodium oxybutyrate increases blood pressure.

If there is no anesthesiologist, then a combination of drugs is administered intramuscularly: promedol 2 ml or moradol 1 ml, diphenhydramine 20 mg, seduxen 20 mg. The use of electroanalgesia with pulsed currents can be successful.

After rest, a vaginal examination is performed to assess the obstetric situation.

The main method of treating weakness of the generic forces is to stimulate the contractile activity of the uterus.

Before stimulating labor, it is necessary to assess the condition of the fetus using a cardiac monitor study.

For rhodostimulation with primary weakness of generic forces, the following methods are used:

Intravenous drip of oxytocin;

Intravenous drip of prostaglandin E2 (prostenon);

Vaginal administration of prostaglandin E2 tablets (prostin);

Intravenous administration of prostaglandin F2a (enzaprost, dinoprost);

Combined intravenous drip of prostaglandin F2a and oxytocin.

Intravenous administration of oxytocin. Oxytocin has a strong uterotonic effect on the smooth muscle cells of the uterus, increases its tone, synchronizes the action of muscle bundles, and stimulates the synthesis of PGR2a by the decidual tissue and myometrium. The reaction of the uterus to oxytocin is ambiguous at the beginning and during the development of labor, since the number of oxytocin receptors increases closer to the end of labor (the end of the first, second, third periods of labor). It is by the period of fetal expulsion that oxytocin becomes a strong stimulant for the synthesis of PGR2 (X. Oxytocin is most effective when opening the uterine os by 5 cm or more.

When using oxytocin for the purpose of labor stimulation, you need to know that exogenously administered it reduces the production of your own endogenous oxytocin. Termination of intravenous administration of the drug can cause a secondary weakening of labor activity, and long-term administration for many hours can cause hypertensive and antidiuretic effects.

Oxytocin does not adversely affect a healthy fetus. In chronic fetal hypoxia, it suppresses the surfactant system of the fetal lungs, which in turn contributes to intrauterine aspiration of amniotic fluid, in addition, it can lead to impaired blood circulation in the fetus and even to its intranatal death.

It is advisable to use oxytocin when the amniotic sac is opened!

The introduction of oxytocin can be combined with epidural anesthesia or with antispasmodic, analgesic agents: no-shpa (2-4 ml), aprofen (1 ml of a 1% solution), promedol (1 ml of a 2% solution).

Method of administration of oxytocin: 5 IU of oxytocin is diluted in 500 ml of 5% glucose solution (dextrose) or isotonic sodium chloride solution. Intravenous infusion is started at a rate of 1 ml / min (10 drops / min), every 15 minutes the dose is increased by 10 drops. In this case, the maximum speed is 40 drops / min. It is advisable to use an infusion pump to administer oxytocin.

Against the background of an adequate dosage of oxytocin, labor activity should also reach its maximum - 3-5 contractions in 10 minutes.

For the prevention of aspiration syndrome in the fetus with any type of rhodostimulation, seduxen (10-20 mg) is administered.

Childbirth with the introduction of labor-stimulating agents is carried out under cardiomonitoring control.

If the introduction of oxytocin for 1.5-2 hours does not give the desired clinical effect or the condition of the fetus worsens, then the pregnant woman should be delivered by caesarean section.

With the clinical effect of stimulation of labor activity with oxytocin, in order to avoid hypotonic bleeding, it is necessary to continue its administration after the birth of the fetus - in the afterbirth and early postpartum periods. Immediately after the birth of the fetus, additional prophylaxis of bleeding should be carried out by intravenous simultaneous administration of methylergometrine.

Intravenous administration of prostaglandin F2? used mainly in the latent phase of childbirth with insufficient "maturity" of the cervix and the primary weakness of the labor force. Unlike oxytocin and PGR2oc, PGE2 has important positive properties for the fetus:

PGE2 causes synchronous, coordinated contractions of the uterus with a fairly complete relaxation of it, which does not disturb the uteroplacental and fetal-placental blood flow;

Stimulates the activity of the sympathetic-adrenal system, suppressing the hyperactivity of the cholinergic nervous system, therefore does not cause hypertonicity of the lower segment or cervical dystocia;

Moderately activates the synthesis of PGR2a and oxytocin without causing hyperstimulation;

Improves peripheral blood flow, restores microcirculation;

The effectiveness of prostaglandin E2 does not depend on the level of estrogen saturation; with hypoestrogenism, it changes the mechanism for preparing the cervix for childbirth, accelerating this process tenfold;

It does not have a hypertensive and antidiuretic effect, therefore it can be used in women in labor with preeclampsia, arterial hypertension and kidney disease;

A softer contraction of the uterus without any spastic component eliminates venous congestion in the sinus collectors, which contributes to a better arterial blood supply to the uterus, placenta, and indirectly to the fetus.

PGE2 preparations are less effective in case of weakness of attempts, weakening of labor activity at the end of the period of disclosure.

The method of administration of PGE2 preparations is similar to oxytocin rhodostimulation: 1 ml of 0.1% or 0.5% prostenon solution is dissolved in 500 or 1000 ml of 5% glucose solution or 0.9% sodium chloride solution (1 ml of the solution contains 1 μg of the active substance ) and administered intravenously at a rate of 10 drops / min, increasing the dose depending on the response to the drug every 15 minutes by 8 drops. The maximum dose is 40 drops / min. For solution infusion, it is preferable to use automatic and semi-automatic systems that allow taking into account the dose of the administered drug.

Contraindications for the use of prostenon are bronchial asthma, blood diseases, individual intolerance to the drug, which is rare.

Vaginal tablets prostaglandin E2. The preparation of prostaglandin E2 - prostin, containing 0.5 mg of dinoprostone, is injected into the posterior fornix of the vagina three times with a break of 1 hour. myometrium. It is prescribed in the latent phase of labor, with a whole fetal bladder, since otherwise prosterone can enter the uterine cavity and cause hyperstimulation.

If labor activity has intensified and labor has entered the active phase, further use of the drug is not advisable. This type of rhodostimulation is contraindicated in case of rupture of amniotic fluid and in case of secondary weakness of labor activity and weakness of attempts.

Intravenous administration of prostaglandin E2. Preparations of prostaglandin P2a are strong stimulators of contractile activity of the uterus. They act on alpha-adrenergic receptors of smooth muscle cells, simultaneously increase the activity of the sympathetic-adrenal and cholinergic autonomic nervous systems, actively interact with oxytocin and PGE2- They have a vasoconstrictor effect, cause and increase arterial hypertension, increase blood clotting, platelet aggregation and adhesion. With untimely use of PGR2a or overdose, nausea, vomiting, and hypertonicity of the lower uterine segment may occur. Shows its effect regardless of estrogen saturation.

Method of administration: one ampoule of prostin or exaprost containing 5 mg of PGR2a is diluted in isotonic sodium chloride solution or 5% glucose solution at the rate of 1 mg per 1000 ml (1 μg per 1 ml of solution) and injected intravenously at a rate of 10 drops / min, increasing the dose every 15 minutes by 8 drops, but not more than 40 drops / min. An indication for this type of rhodostimulation is the weakness of labor activity.

A significant effect in the treatment of weakness of patrimonial forces was obtained by combining prostaglandin E2a with oxytocin.

With combined intravenous administration of prostaglandin E2? and oxytocin, the dosage of both drugs is reduced by half (2.5 mg and 2.5 U), diluted in 500 ml of 5% glucose solution and administered intravenously at a rate of 8 drops / min, adding 8 drops every 15 minutes, bringing up to 40 drops / min (maximum dosage).

With the simultaneous administration of oxytocin and prostaglandin E2? their potentiated action is noted.