Calculate the term by the last monthly. How to determine the gestational age: the most accurate ways

10.09.2019

Each representative of the fair sex, having learned that she is in a position, seeks to calculate the exact duration of pregnancy as soon as possible. It can be used to calculate the approximate date of birth of the long-awaited baby. Determination of the gestational age is also required by the gynecologist to track the development of the fetus, identify violations, timely prescribe tests and examinations.

How do doctors determine the gestational age?

For women who come to a medical institution and claim that they are pregnant, the gynecologist first of all asks when they had their last periods. It is from this date that he will count down. Interesting, right? Fertilization has not yet occurred, since it occurs during ovulation in the middle of the cycle, and obstetricians start counting from such an early date.

This method for determining the duration of pregnancy and childbirth is called " obstetric». True the term of the interesting situation is about 2 less than the term that the doctor tells the pregnant woman. The minimum period for determining pregnancy with this method is 2-3 weeks.

You can find out the time by the results of an ultrasound scan. Their accuracy will be less in the later stages, because each baby develops in the mother's tummy in its own way. The doctor determines the duration of pregnancy by the size of the fetus. The following indicators are measured:

biparietal size, defined between the temporal bones (BPD);
frontal-occipital size (LZR);
head circumference (OG);
abdominal circumference (coolant);
thigh length (DLB);
chest diameter (DHRK), etc.

Each week is characterized by certain values of the above criteria. The gynecologist uses a special table for determining the timing of pregnancy for the calculation.

The doctor can determine the period of an interesting position according to the size of the uterus during the gynecological examination. For example, at the 4th week of pregnancy, the organ can be compared with a chicken egg, and at the 8th week - with a goose egg. It is difficult to establish a term for the size of the uterus later.

How else do doctors determine the gestational age? For example, a method is used to determine the duration of the position along the length of the uterus. A pelvimeter or a measuring tape is used. Typically, the number of weeks is equal to the length of the uterus. For example, during the measurement, it turned out that the length of the uterus is 34 cm. This means that the period is 34 weeks. To obtain reliable results, a woman is advised to empty her bladder before visiting a doctor.

How to determine the duration of pregnancy at home?

A pregnant woman can independently calculate the period of her interesting situation without the help of doctors. How to find out the duration of pregnancy at home? There are several ways:

by the last menstruation;
by date of conception
by the first stirring of the crumbs;
using an online calculator.

1. How to determine the duration of pregnancy by the last menstruation?

The easiest way for doctors and many women to find out the gestational age is by the last menstruation. How to determine the very term of pregnancy by the last menstruation? It is necessary to count the number of weeks between the date of the onset of menstruation and the date of the calculation. This will be the gestational age.

By the date of the last menstrual period, it is convenient to calculate the date of birth. There is a special Negel formula. From the date of the last menstruation, 3 months are counted back and 7 days are added.

Calculation of pregnancy by the last months is a fairly simple but inaccurate method, since it is more than the true period by a couple of weeks.

2. How to determine the duration of pregnancy by the date of conception?

Recall that conception occurs approximately in the middle of the cycle after the release of a mature egg from the ovary (ovulation) during the day. The method of calculating the gestational age by the date of conception is suitable for those women who know exactly when they ovulated. The term of pregnancy is determined by week. The countdown is from the date of ovulation. You can also use averages (for example, with a 28-day cycle, ovulation occurs approximately on day 14, that is, in the middle of the cycle). And how to determine the duration of pregnancy with an irregular cycle? In such cases, approximate values will not work.

The moment of release of an egg ready for fertilization can be found out using special tests, basal temperature or ultrasound results. Some women determine ovulation by how they feel (by the presence of pain in the lower abdomen, abundant discharge from the penis, increased libido). If the date of ovulation (and, accordingly, the date of conception) is unknown, then using the method of determining the gestational age by the date of conception will not work, since the results will not be accurate.

3. How to determine the gestational age by the first stirring?

The baby begins to move in the tummy of the mother, whose pregnancy is the first, from the 20th week. Multiparous representatives of the fair sex begin to feel movements from the 18th week.

It is worth noting that using this method it is not always possible to find out the exact date. Some women feel the first movements much earlier than the indicated weeks, and some, on the contrary, later. Most doctors note that women often confuse the first movements with the "work" of the intestines, because it is known that many pregnant women suffer from increased gas production.

4. How to determine the term of pregnancy using a calculator?

To calculate the gestational age, you can use the calculator below. His work is based on the method of determining the term by the last months, which was described above. How to determine the duration of pregnancy using an online calculator? In order to use it, you need to know the start date of the last menstrual period, the average duration of the menstrual cycle and the luteal phase. The calculation results will be known immediately.

Summing up all of the above, I would like to note that many women are interested in the question of how to accurately determine the duration of pregnancy. However, with almost all of the above methods, it may not be calculated accurately. The only exceptions are cases when a pregnant woman knows the exact day of ovulation. Do I need to know the absolutely exact date of an interesting position? It is worth noting that it is not that important. Deviations of a few days or a week will not play a big role, so do not be afraid if the exact day of ovulation and conception is not known.

Replies

As soon as a woman becomes pregnant, she is immediately interested in the question: how to independently determine the gestational age at home? Indeed, with the help of such calculations, you can calculate the approximate date of birth of your child. In addition, the expectant mother may not know the exact day of conception.

Some people try to calculate the onset of pregnancy by the timing of ovulation, but you should know that ovulation occurs between the 8th and 16th day of the cycle. Therefore, fertilization can occur in the interval already from the 8th to the 18th day of the menstrual cycle, given the viability of sperm in the genital tract of a woman. Indeed, it is in this case that conception most often occurs. In addition, the duration of pregnancy may not be 40 weeks, since a normal pregnancy is already full-term by 37-38 weeks, therefore, after this period, labor can begin at any time.

Even a pregnant woman may have more than one fetus, so childbirth can occur 2-3 weeks earlier than with one fetal pregnancy. Also, any individual characteristics of a woman can affect childbirth, it can be diseases, for example, diabetes mellitus, hypertension or other diseases. But, despite this, it is still possible to determine the approximate duration of pregnancy at home.

Determination of the gestational age, regarding ovulation and the date of conception

You can correctly determine the exact duration of pregnancy using the calendar. As you know, ovulation is the period of the menstrual cycle in which the conception of the child begins. And during ovulation, a mature egg comes out of the female ovary into the fallopian tube, which is met by the sperm. As a result, pregnancy occurs. By the date of ovulation, the gestational age is determined. There are little tips on how to recognize pregnancy symptoms in a woman.

A woman ovulates around the middle of her menstrual cycle. And if a woman's cycle is about 28 days, then ovulation will occur at about 14 days. And when a woman's menstrual cycle is 35 days, then ovulation will be on the 17-18th day of the menstrual cycle. Therefore, the exact duration of pregnancy should be counted from the day of ovulation. Moreover, knowing the day of ovulation, you can plan a pregnancy and know the month and the approximate date when the baby will be born.

It is worth noting that you can easily determine your ovulation yourself at home and using ovulation tests that are sold in a pharmacy, or you can determine by measuring your basal temperature. To do this, you will need to cleanse the intestines at home using an enema, and then measure the temperature in the rectum with a thermometer. Peculiarities:

Throughout the first half of the menstrual cycle, the basal temperature is kept at around 37 degrees.
The day before ovulation, it decreases slightly.
On the day of ovulation and all subsequent days, the temperature will rise and will be 37-37.2 degrees.

Therefore, how to accurately determine what is my pregnancy period by the date of ovulation, you can use a conventional thermometer.

However, there are women who know how to determine the gestational age, focusing on their subjective feelings. And these sensations include pain in the lower abdomen, an increase in the amount of vaginal discharge, or an increase in libido. In addition, in some cases, a woman's pain during menstruation may disappear, which indicates any positive changes.

Therefore, it is not difficult for such sensitive women to determine the time when conception occurred. But still, the most accurate way to determine the duration of pregnancy is an ultrasound scan. In addition, with the help of this study, you can find out the date of ovulation. However, constant trips to the ultrasound office will require a lot of money, so you can try more affordable methods for calculating the gestational age.

Determining the duration of pregnancy, relative to the date of the last menstruation

This is perhaps the simplest and most well-known method for determining the juices of pregnancy and it is called the Negele method. However, this method is more helpful in calculating the due date, rather than pregnancy. According to this method, to determine the timing of childbirth, it will take three months from the first day of the last menstruation, and then add seven days to the number. And in accordance with the received date of birth, you can easily calculate the duration of your pregnancy.

Determination of the gestational age, thanks to an experienced gynecological examination

Without a doubt, if a woman came to a gynecologist for an examination in the very first weeks of pregnancy, for example 3-4 weeks, then it will not be difficult for him to determine the gestational age. And in this case, the specialist determines the duration of pregnancy by the size of the uterus.

It will not be difficult even during a period when a woman just recently took a pregnancy test and immediately came to the gynecologist.

For example, at 4 weeks, its size can be compared to a chicken egg, and at 8 weeks, the size of the uterus can be compared to a goose's egg. And if this is a very experienced gynecologist, then the obstetric examination will be professional, as a result, he can determine the gestational age with the help of a vaginal examination and set the date with an accuracy of one day.

After a period of 8-12 weeks, it is very difficult for a gynecologist to determine the size of the uterus with a period, since every woman has a uterus and its size may differ. Therefore, the gynecologist can not only determine a more accurate date, but also provide a full briefing on what can be done by pregnant women. For example, swimming is beneficial for pregnant women or not, or what exercises or exercises should be done to correct posture and strengthen muscle tone. During this period, an experienced doctor can determine the sex of the unborn child or several at once.
Determining the term of pregnancy using the result of modern ultrasound examination can be more likely to determine the exact term if ultrasound is performed in the early stages, this is 8-12 weeks. At longer periods, each child develops differently, so it will be difficult to determine the exact date. And if the fetus is gaining insufficient weight after 20 weeks of pregnancy, then this examination is used to diagnose poor fetal development.

Usually such a diagnosis is given to women of fragile physique. And on the one hand, this is wrong, because a full-term baby can weigh 2.8 kg or 4 kg. Therefore, the weight and size of each child can vary significantly. For this reason, it is not necessary to pay attention to the period that is set for ultrasound in the 2-3 trimester of pregnancy.

Useful materials:

After all, the determination of this period will help to calculate the approximate date of when the long-awaited child will be born. There are a lot of methods, and it's hard to say which one is the most accurate. But it is quite possible to determine which week of pregnancy you are at home on your own.

Medical examination methods

Consider how doctors determine the gestational age:

By ultrasound. This is one of the most common ways. The doctor measures the size of the fetus, and according to them he already calls your period approximately.
By the date of the last menstruation. This is how you can tell when ovulation has occurred.
By the size of the uterus. With each week of pregnancy, the uterus changes, increases in size and rises higher.
HCG analysis. It shows the amount of hormones in the blood. The method is quite accurate, but still does not give an unambiguous result.

Pregnancy: how to determine its term at home

Some women prefer not to go to doctors right away because they know how to find out early pregnancy at home. There are quite a few methods, here are some of them:

By the date of ovulation.
For the last menstruation.
By the wiggle of the baby.
By date of conception.
Formula Negele.

Early pregnancy detection at home

If you do not have a test at hand, then there are other ways to find out early pregnancy at home:

With baking soda.

Take a small container and fill it with morning urine. Add a spoonful of baking soda there and watch carefully what happens. If the baking soda reacts and starts to sizzle, then you are not pregnant. And if it precipitates, then you will soon become a mother.

With iodine.

You will need a container filled with morning urine. You need to add a small drop of iodine to it. In the event that the drop remains on the surface, then you are pregnant, and if it dissolves, then no.

Ovulation: how to determine the gestational age by it

Ovulation is the period in the menstrual cycle when a woman can become pregnant. At this time, the egg matures, then goes into the fallopian tube and stays there for a certain period of time in order to wait for the sperm.

If you want to understand how to find out the gestational age by the date of ovulation, then you should have a schedule for maintaining basal body temperature. By the way, in pharmacies you can find tests that help to accurately determine ovulation. If intercourse occurred during this period, then most likely you are pregnant.

Determine the term by the last monthly

Finding out the gestational age by the last menstruation is another way that you can use at home, without the help of doctors. The first day of the last menstrual cycle is the period when the egg matures, the body is completely rebuilt and conception is at the maximum possible.

It is very easy to find out the gestational age by the last menstruation. Count how many weeks have passed from this date to the present - that's all.

Take a calendar and add 280 days to this date. This is approximately 40 weeks (this is how long the pregnancy itself lasts). It will be an approximate time, you have to give birth to your child.

It is easiest to find out the gestational age by the last menstruation. It is for this reason that women use it at home. Not everyone can measure their basal temperature and determine the period of ovulation, but the date of the onset of menstruation is recorded by everyone.

When the baby begins to move in the womb

Any representative of the fair sex who is preparing for the role of a mother is very sensitive to the period of bearing a baby. Many questions arise regarding pregnancy and childbirth. Someone is trying to find out the duration of pregnancy by menstruation, someone uses other methods.

It should be noted that it is almost impossible to determine the exact date. But, if you calculate it in several ways, then the probability will increase. For example, you have already calculated the period for menstruation, now wait until you feel the first movement of the baby.

In primiparous women, this usually happens at 20 weeks, in multiparous women it can happen earlier. In any case, when you feel that the baby in the womb began to move, you will know that you are now about 20 weeks pregnant.

Date of conception: how to calculate the gestational age with it

Determining what week of pregnancy you are at the moment is possible only if you know exactly the date when conception occurred. Otherwise, only a gynecologist can do this.

To find out the duration of pregnancy by weeks and days, make an appointment for an examination, the doctor will find out from you the date of the first day of the last menstruation and calculate the obstetric period, and name the approximate date of delivery. Do not forget that this is only an approximate date. Only your baby knows when he will be born. It is possible to find out the gestational age by weeks and days quite accurately, but you should not rely on the date of birth.

Formula Negele

The Negele formula is the easiest way to find out the approximate date of birth.

We take the first day of your last period and subtract three months from it.
7 days are added to the resulting date.
The final date is the approximate time when the baby will be born.

The exact period of pregnancy - is it really possible to know it

Most women are interested in the question of how to find out the exact term of pregnancy. Doing this at home is problematic, because any method deviates from the truth. If you want to get more reliable information, then you can do this in the following ways:

Ultrasound procedure.

The exact date of the ultrasound can only show in the early stages. The fact is that embryos develop equally only in the first 3-4 weeks after conception. Further, the embryo develops in each girl differently.

Gynecological examination.

How to find out the exact duration of pregnancy at a gynecological examination? The doctor measures the uterus, sometimes even determines the position of the fetus at this stage. According to the data obtained, it is possible to understand what week of pregnancy the woman is in, because the uterus is constantly changing and there are standards for how this should happen.

Boy or girl

It is not soon to do an ultrasound examination, and the expectant mother is already overwhelmed with interest, who will she give birth to - a boy or a girl? It is worth noting that ultrasound sometimes fails to determine the sex of the child. Some parents are happy about this, because they want a surprise, while others, on the contrary, want to know everything at once.

You can find out the sex of the baby in early pregnancy in the following ways:

By the intensity of sexual activity.

If the conception of a child occurred during the period when the couple was sexually active, then it is more likely that a boy will be born. The fact is that mobile "male" spermatozoa do not live very long. Therefore, when a man rarely has sexual intercourse, the body has a greater vitality of "female" sperm. This has been proven scientifically.

For the purity of blood.

The sex of the child is very often determined depending on which of the spouses has newer blood. It is believed that in women the blood is renewed once every 3 years, and in men every 4 years. If at the time when conception occurred, the man's blood is newer, then there will be a boy, if the woman has a girl.

According to the formula.

Our grandparents very often used the formula to determine the gender of their unborn child. It looks like this: 49-X + 1 + Y + 3. Y is the month of conception and X is the father's age. Plug in all the data and calculate what you get. If the number is odd, it means that the probability that a girl will be born is higher, and if it is even, a boy.

For a woman.

They say that if a woman becomes prettier during pregnancy, then she is expecting a boy, because boys take care of their mother and give her beauty. With girls, the situation is the opposite, they take away the beauty. Therefore, if you notice that the hair has become less frequent, the nails are peeling, the skin is dry - this means that, most likely, you will give birth to a representative of the fair sex.

Which method is most accurate

Every woman is interested in how to find out how long she is pregnant, and at least the approximate date when she will give birth. All of the above methods are good in their own way, but none of them can give you a clear answer to this question.

The fact is that each representative of the fair sex is special, like her body, and when the baby decides that he is ready to be born, only he himself knows. This can happen several weeks earlier if the fruit is ripe. If the baby is not yet ready to leave the womb, then the pregnancy is delayed for several more weeks.

Now you know how to find out the term of pregnancy at home, as doctors do. Moreover, if the ultrasound does not show the sex of the child, then thanks to the methods listed above, you can determine this yourself. Even if the result is unreliable, it is still interesting. After the baby is born, you can determine which method turned out to be true for you.

(lasting 28 days), or 280 days. In reality, these terms fit into 9 calendar months, plus seven days. Therefore, it is customary to talk about 9 months. The birth of a baby at 38-42 is considered normal if absent, indicating immaturity or overmaturity. If the baby was born later than this period, then it is considered post-term, otherwise - premature.

Obstetricians-gynecologists begin the countdown of pregnancy from the first day of the last menstrual period. Usually, the actual period is 13-16 days less, since conception occurs approximately in the middle of the menstrual cycle, i.e. at the time of ovulation. However, to avoid confusion, doctors start counting pregnancy 2 weeks ahead of date.

If you do not know the exact date of conception, then it is most correct to count the weeks of pregnancy based on the results of an ultrasound scan. Routine research is carried out at 12-13. As a rule, it coincides with the deadline set at the first appointment. But, if there are discrepancies, then it is better to focus on the term set with the help of ultrasound.

In some cases, there may be a discrepancy between the size of the fetus and the gestational age. For example, as a result of polyhydramnios, the presence of tumors, etc. These data are taken into account by specialists in the study. In this case, the number of weeks of pregnancy is set, obtained from the calculation of the first day of the last menstruation, and with the help of ultrasound, it is corrected at later ones.

Pregnancy term - what is it?

After ovulation, when the egg is released from the ovary, it lives for 24 hours. This time is considered the most favorable for conceiving a child. When the cycle equates to 28 days, ovulation occurs on the 14th day from the start of menstruation. The sperm cell meets the egg, fertilizes it, and after a week the embryo attaches to the inner lining of the uterine wall.

It is sometimes impossible to calculate the exact date of ovulation and conception. Therefore, doctors take as the beginning of pregnancy the 1st day of the last menstruation, and exactly 280 days later, delivery should occur. As a result, a paradox arises: the period began to be counted when the pregnancy itself was not yet. Therefore, it should be understood that the embryo exists approximately 14 days less than the set date.

The following methods are available to determine the gestational age and due date:

Ultrasound examination.

Using the Negele formula.

Determination of the level of hCG.

Measurement of the uterus during examination in the gynecologist's office.

Assessment of your own feelings (according to fetal movements).

Obstetricians to determine the gestational age are guided by the data of an ultrasound examination. You can clarify them with the help of a gynecological examination of the uterus, as well as knowing the date of the last menstruation.

Ultrasound

Ultrasound is the basic method for determining the duration of pregnancy. You can count on the maximum reliability only when the procedure is carried out 10-12 weeks after fertilization. In the future, ultrasound will not allow you to accurately determine the duration of pregnancy and the date of the expected birth. Therefore, it is so important to undergo an ultrasound scan in the 1st trimester of pregnancy.

The devices used by diagnosticians allow you to fix a three-week-old fertilized egg. The date of conception and the date of the expected birth are calculated by the doctor based on an assessment of the coccygeal-parietal size of the embryo. This indicator can be determined after they reach 3 cm or more. Based on the results of an ultrasound scan, the doctor issues a conclusion. It indicates the embryonic and obstetric gestational age. The first characterizes it from the moment of conception, and the second - from the day the last menstruation began.

When the fetus reaches 22 weeks, it will not be possible to accurately determine its age. However, at this time, doctors assess the main criteria for the intrauterine development of the child. Measured by the size of the head, the circumference of the abdomen, the length of his femur. If fetal indicators do not match its age, then intrauterine growth retardation can be suspected.

It should be understood that there are individual characteristics that the baby inherits, for example, short stature or a large head circumference. They appear in the third trimester, so it will be impossible to calculate the gestational age by ultrasound.

Determining the duration of pregnancy by the date of the last menstruation

If a woman's cycle is equal to 28 days, then it will not be difficult for her to calculate the date of birth on her own. To do this, you need to use the Negele formula:

"PMP (the first day of the last menstruation) - 3 months + 7 days = PMD (estimated date of birth)"

Calculation example: PMP was on August 16, which means August 16 - 3 months + 7 days = May 23. On this day, childbirth will take place. In this way, everyone calculates the date of birth.

Cases when it is not possible to determine the duration of pregnancy by menstruation:

Your menstrual cycle is irregular or too long. If it exceeds 35 days, then ovulation will not occur on day 14, so it is impossible to calculate the exact date of birth using the Negele formula.

If there is a risk of miscarriage during early pregnancy. The main sign of a threat is often the appearance of scanty bloody discharge. A woman may confuse them with menstrual bleeding, and will not even guess what is in the position. In this case, ultrasound can help in determining the duration of pregnancy.

If the woman is taking birth control pills. When the regularity of the scheme is disrupted, there is a chance of getting pregnant. Ovulation in this case happens suddenly, so it is impossible to calculate the exact date of its occurrence.

Examination of a woman on a gynecological chair

Every woman must be examined by a gynecologist before being registered.

It defines parameters such as:

The height of the fundus of the uterus;

The size of the uterus.

These indicators suggest the gestational age, if not accurate, then approximate. The error in the definition is due to the individual characteristics of the location of the uterus. In addition, a full bladder and the presence of fibroids can make examination difficult. In the event that a woman is carrying 2 or 3 babies, the uterus will be enlarged more than usual, which will also affect the accuracy of timing.

Determining the duration of pregnancy by the level of hCG

8-10 days after the conception occurred in the woman's body, the level of chorionic gonadotropin (pregnancy hormone) begins to increase. Every day this figure will double.

It should be understood that it is impossible to determine the gestational period with 100% accuracy by the level of hCG. The fact is that the boundaries of its norm for each week of pregnancy vary quite widely. Moreover, the hCG indicator can go off scale when carrying twins or triplets, as well as with various pathologies of pregnancy.

As practice shows, a woman begins to feel the first movements with. This pattern is legitimate for those expectant mothers who give birth for the first time.

If the birth is the second or more, then the woman can feel the movements of the baby already on -.

It is impossible to determine the gestational period for this indicator by 100%. Sensitivity will be influenced by factors such as the thickness of the fat layer between the uterus and the peritoneum, the individual characteristics of the fetus, etc. In addition, when a woman really wants to feel life inside herself, she can even take the passage of gases through the intestines for fetal movements.

How to calculate the gestational age after IVF?

Many expectant mothers have questions about the reliability of calculating the gestational age after artificial insemination, because an already developing embryo is placed in the uterine cavity.

Gynecologists calculate the gestational age, starting from 1 day of the last menstruation, and it does not matter in what way the conception was carried out. However, there is an exception to this rule: with IVF with a menstruation suppression protocol, 14 days are added to the day of embryo replanting, and only from this date the gestation period begins.

Why do you need to know the exact duration of pregnancy?

The gestational age is an important indicator that acts as a guideline for doctors in the following points:

Determining the date of birth of the child;

Assessment of the development of the fetus;

Planning for prenatal screening for chromosomal abnormalities;

Assessment of the child's ability to survive outside the womb in the event of his early birth.

A woman's knowledge of the gestational age will allow her to psychologically prepare for the date of the upcoming birth, as well as provide information about what is happening with the baby at one time or another of his intrauterine life.