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Determine the duration of pregnancy by monthly calculator. We calculate the gestational age and the date of birth by conception on the days of ovulation. Determination of the gestational age, thanks to an experienced gynecological examination

Determining the gestational age by the date of the last menstruation is called obstetric method. This calculation is not accurate, the calculation is made from the beginning last menstrual period, of course, it is impossible to get pregnant during this period, since the fertilizing process occurs much later.

Determination of the gestational age: why is it necessary

  • determination of the gestational age indicates indicative date childbirth;
  • the date of the last menstruation allows you to determine the beginning of maternity leave;
  • the correct calculation of pregnancy allows you to observe the formation of the fetus in stages (it is necessary to identify deviations).

Depending on the term, the expectant mother will be able to take some preparation actions. Someone wants to buy everything they need during pregnancy, someone has a specially designed monthly diet.

Doctors also monitor weight future mother based on her term. The fruit should not be too large, so that there is no pathological childbirth because of the narrow pelvis.

Depending on the calculation of pregnancy, the woman is determined with the date of the beginning of the baby's movements and, of course, patiently counts the days.

What are the terms of pregnancy

The entire cycle of a pregnant woman takes 39-42 weeks. The specific number of conception that occurred cannot be accurately calculated.

Current obstetrics calculates the period from the first day of the last menstruation. This calculation is based on 40 weeks, since the formation of the egg occurs 14 days from the start critical days. Often, the date calculated by the woman in labor and the profile doctor does not match, which leads to panic for the future parent.

Determining the gestational age by the date of the last menstruation is not the only term (obstetric) - there is still a true one (embryonic).

The calculation of the term of the embryo (true) differs from the obstetric calculation by approximately 14 days. This is due to the fact that the doctor counts from the first day of the last critical days before the woman became pregnant.

Gynecologists most often use this method for their calculations. Determining the gestational age by the date of the last menstruation, the doctor calculates the dimensions of the embryo, maternity leave, the number of expected births.

For more accurate studies on possible genetic abnormalities and the pathological direction of the process, an ultrasound examination with blood tests is required, however, this occurs in specific weeks of fetal development.

Obstetric method for determining pregnancy: how it works

The term of obstetric calculation is calculated very simply. A nine-month period is taken, to which another 7 days are added. The result is 287 days. Doctors have been using this method for many years.

Logically, every woman knew that until she had her monthly period, she was not pregnant. Based on this, our ancestors formed a count. From the first day of the last menstruation to the onset labor activity 280 days pass. This method has successfully passed to specialists in obstetric practice.

Determining the period in pregnant women, modern gynecology has reverse order. From the date of the first day of the last critical days, 90 days are subtracted and 7 days are added.

For example: according to the last monthly cycle it was April 1, subtracting one trimester, you get January. Next, the birth day is calculated: by January 1, 7 days are added, the eighth number is obtained. So, presumably, the birth will come on January 8th.

Is it possible to get pregnant on the first day of menstruation? Of course not, but from this moment the maturation of the egg begins, which could be fertilized in the future. The given date is not exact, most likely estimated. An ultrasound study provides more accurate information.

The gestational age, according to obstetric calculations, differs from the true one by 14 days- he gets more. Individuality must also be taken into account. embryonic development- they can be different. It depends on some factors:

  • heredity;
  • feature of the regularity of cycles.

If there are such individualities, then it is required from the estimated term of the obstetrician to subtract 14 days, the term of the embryo will be obtained.

How to find out the date of birth by the date of the last menstruation

Most often, the date of birth is calculated according to the Negele formula - calculation by the number and month of the last critical days. This formula is used for special obstetric calendars.


Determining the gestational age by the date of the last menstruation is most often calculated using the Negele formula

The calculation according to the formula is as follows. Forty weeks added to last menstrual date, however, this calculation is far from the truth, and is not considered accurate. Most women who have calculated their pregnancy and know the date of conception add 10 months to it lunar calendar. They get the date of birth, which often does not correspond to the one set by the doctor.

What is an online calculator for determining the duration of pregnancy

There is an online calculator. IN Lately, this service has proven to be very useful, accurate and important for all expectant mothers.

All stages of pregnancy have some small nuances that should be taken as a fact. The purpose of the program is aimed at an instant calculation of the period by which changes in the body of the mother and child are determined.

The online calculator helps the future woman in labor to track and control the whole process until the birth day - this is the most exact way.

The online service allows you to find out more the exact date the birth of a child, its results most often coincide with the real term, which cannot be said about obstetric counts. Knowing the exact number, it is possible to plan certain events.

How else can you determine the gestational age if there is no date for the last menstruation

Women often confuse baby movements with changes in the intestines, so you need to monitor the dynamics of new sensations that appear.

Determination of the date for the first visit to the doctor

When a woman appears for an appointment with a specialist, the doctor, upon detection of pregnancy, puts her under accounting control. When examining a woman, the gynecologist examines her on a chair, determines the size of the uterus with her hands.

Plasma analysis shows chorionic gonadotropin. From these indicators, after admission, the physician determines the gestational age and the approximate date of the birth of the baby.

The best results of determining the term are observed in those mothers who visited the doctor during (up to twelve weeks). The doctor can already well examine the uterus at a five-week period. The organ increases, rounds, becomes softer. If the timing is already longer, then the size of the uterus varies. This is due to the size of the baby, the amount of water, the construction of the inner pelvis.


Measurement of KTR - coccygeal-parietal size - of the fetus allows you to more accurately determine the gestational age

Ultrasound examination

On ultrasound examination it is possible to recognize pregnancy at an early stage, measure the fetal egg and embryo, and also determine the correct date with considerable certainty.

A small round darkening is visible on the monitor at a four-week period - this is the fertilized egg, in which the embryo will be located. By seven weeks, a tiny strip is already visible and a heartbeat is visible.

Measurement of KTP (coccygeal-parietal dimensions) - an accurate calculation of the term. It is determined by the distance from the coccyx of the fetus to its head. When the period reaches 11-13 weeks, you can determine the size of the head, tummy, the length of the arms, legs, and more.

Up to 2.5 months, the fetus grows with proportionality, and in almost all women the sizes are identical. Then there are changes individually, based on nationality, body weight. Body weight plays an important role in the birth of future parents.

In ancient times, people believed that to calculate approximate weight a child can be added by adding the mass of the mother and father at birth, dividing in half. The resulting number is the approximate weight of the future newborn. This explains the fact that over long periods of time, with normal development, y different women different sizes fetus.

For long periods on ultrasound it is impossible to calculate the individual date of birth so every baby is different genetic feature body structure, weight, height, head circumference.

Each woman in labor seeks to know the date of the birth of the long-awaited crumbs. Modern young mothers are increasingly trusting online programs, of course, not excluding the recommendations and instructions of the doctor, because it is quite difficult to determine the absolute accuracy.

What is the definition of gestational age by the date of the last menstruation:

The gynecologist tells about determining the gestational age:

The long-awaited pregnancy has come, and you really want to know when you will see your baby? To calculate the gestational age and the expected day of birth, it is enough to know only one date: the day the last menstruation began. It is for her that the gestational age will be calculated by the gynecologist when you come to the clinic to be registered.

Calculate gestational age online

Only a few women can accurately name the date of conception of a child in order to accurately calculate real term pregnancy. And even in this case, the birth of a new life may occur on another day, when future parents do not know about it. At the same time, almost every woman remembers the date of the last menstruation, which is why it is her obstetricians who take it as a starting point. Theoretically, ovulation - the period of the release of an egg ready for fertilization - occurs in the middle of the menstrual cycle. Therefore, between the real age of the fetus and the obstetric gestational age (which begins on the first day of the last menstruation), there is a difference of approximately two weeks.

So, in order to calculate the gestational age online, you need to remember when your last period started. Two weeks are added to this day: it is during this period that the egg fully matures - and fertilization can occur. Further, there are two ways to calculate the expected date of birth: the first is when forty weeks are added to the date of the first day of the last menstruation. The second - from the day when conception could occur, three months are taken away and seven days are added to it.

But if you don't like fiddling with calculations, the interactive gestational age calculator will do it for you. Enter your data (the date of the first day of the last menstruation) - and within a second you will receive as a result the gestational age in weeks and days.

Calculate gestational age by date of conception

This calculator can also be used to calculate the gestational age by the day of conception if you are sure that this date is accurate. In this case, you will know the actual (gestational) gestational age, which will correspond to the age of the fetus. The obstetric period that the doctor will give you on the first day of the last menstruation will differ from it by about two weeks (that is, there will be more gestational).

Using our calculator to calculate the gestational age by weeks, you can also find out the approximate due date and start preparing for them in advance: find a comfortable maternity hospital and good doctor, learn breathing techniques in childbirth, choose comfortable posture for childbirth, think about partnership childbirth, arrange a nursery and stock up on everything you need to care for a newborn.

Almost every pregnant woman is very interested in when her baby will be born. Accurate technique there is no definition of the day of birth. But there are quite a lot of methods that allow you to calculate the expected date of birth (EDP). How to use these methods, and which one is the most accurate? More on this later!

Determination of the date of birth by the date of conception

By the date of conception, you can set the approximate birthday of the baby. It is known that the conception of a child can occur only during the period of ovulation, i.e. at the time when the finished egg leaves the follicle and goes to meet the spermatozoa.

As a rule, ovulation occurs on the 14th day of the menstrual cycle. Under the menstrual cycle should be understood as a period of time from 1 day of menstruation to 1 day of the next. For each woman, the duration of this cycle is individual. On average, it is 27-29 days, but can stretch up to 35 days or even more.

Women who carefully monitor their menstrual cycle and plan pregnancy are usually able to determine their day of ovulation.

Knowing the date of ovulation, you need to add 280 days to it(namely, how long the average pregnancy lasts for women). You can find out the expected date of birth of a child using this method only if there is a constant menstrual cycle.

At the same time, you need to understand that the day of sexual intercourse is far from always the day of conception, because. the life span of spermatozoa can reach 3 days.

Calculation of due date based on last menstrual period

The approximate birthday of the baby can be calculated from the last menstruation. You need to know the day it started. To determine the approximate date of birth of a child count forward from the first day of the last period 280 days (average duration pregnancy).

According to statistics, no more than 5% of children are born on the “settlement” day. About 85% of babies are born with a deviation of 5-7 days from the calculated due date, and the remaining babies are "in a hurry" or "late" for another extra week. By medical standards normal duration pregnancy is 38-42 weeks, and not strictly 40 weeks, as many for some reason mistakenly believe.

At the same time, a variety of factors can influence the duration of pregnancy, including the individual rate of development of the child and the duration of the menstrual cycle of the expectant mother.

For example, if the cycle lasts up to 24 days, the baby can be born for 1-2 weeks ahead of time calculated using the above formula. If the duration of the menstrual cycle exceeds 32 days, the child may be "late" for the same 1-2 weeks, while such a "delay" will not be considered overdue.

How to calculate due date by ultrasound

Currently, the method of calculating the date of birth by ultrasound is the most reliable. It is only necessary to pay attention to the period of pregnancy in which the study is performed.

For example, if an ultrasound is performed at the 11-14th week of pregnancy, the expected date of birth can be set with an error of 1-3 days.

In the first trimester of pregnancy, the embryos practically do not differ in size. During the second trimester, differences in fetal weight and height can be quite significant, and in the third trimester they become even more pronounced. Therefore, during the 2nd and 3rd trimester, it is unlikely that it will be possible to find out at least the estimated date of birth by ultrasound.

By the first move

At a time when medicine did not yet have the means to carry out ultrasound research, the most reliable way to establish the expected date of birth was the method of determining the first movement of the baby.

Doctors are still interested in the date of the first movement of the child in pregnant patients and note this information in exchange card, but such important this day is no longer attached. But no one is stopping you from trying.

In accordance with this method, women who are pregnant for the first time most often feel the movement of the fetus at the 20th week of pregnancy. Hence, by the day of the first stirring, you need to add the same number of weeks. This will set the expected date of birth.

In the second and subsequent pregnancies, the first movements may appear as early as the 18th week. To determine the expected date of birth in such a situation, you need to add 22 weeks to the day of the first movement.

This method can hardly be called the most accurate. Due to individual physiology, some pregnant women feel fetal movement earlier specified deadlines. In addition to this, many modern moms lead active image life, against the background of which the moment of the first stirring can simply not be noticed.

In the event that a woman is forced to adhere to bed rest according to medical indications, she will certainly feel the movement of the fetus. At the same time, the first movements can be noticed by such women even before the 18th or 20th week.

According to the results of a gynecological examination

During a gynecological examination, the specialist notes the degree of enlargement of the uterus. In accordance with this indicator, it is possible to accurately determine the approximate day of delivery. The uterus increases in size along with the fetus, which is why experienced specialist in most situations can calculate without any problems approximate date childbirth.

According to the size of the uterus during the first trimester of pregnancy, the doctor can determine the length of the pregnancy and therefore calculate the approximate date of delivery, using the approximate day of the last menstruation in the calculations.

At the 2nd and 3rd trimesters, set the date of delivery according to the results gynecological examination very difficult, because in different women, the size of the uterus changes with different intensity. In view of this this method considered ineffective in late pregnancy, and therefore not used.

According to the results of an obstetric examination

In the second half of pregnancy (usually starting from the 20-21st week) during each gynecological examination doctor measures pregnant woman and the height of the bottom of her uterus. Thanks to these measurements, the specialist has the opportunity to monitor the course of pregnancy and timely determine the presence of any kind of abnormality. Also, thanks to this information, the doctor can approximately calculate the date of birth.

However, this method cannot be completely trusted, either. the accuracy of the readings obtained as a result obstetric examination, may depend both on the individual characteristics of the body of the pregnant woman, and on the accuracy of the doctor.

What is the most efficient method?

Most effective method determining the expected date of birth is the method of ultrasound. Also, a relatively high accuracy is shown by the method of counting from the date of the last menstruation. It is very good if the results of the calculations for these two methods coincide - then the chances of the baby being born on the expected day will also increase.

But if the dates do not match, you should not be upset. Carefully monitor the course of your pregnancy and regularly undergo scheduled examinations. Remember: each of the considered methods allows you to determine only the approximate date of birth.

Why are due dates only estimates?

In reality, it is almost impossible to establish the exact date of birth of a child. Only a few women manage to give birth exactly on the day determined by the doctor or on their own. Most often, pregnancy lasts 280 days (40 weeks), but it is not uncommon for mothers to give birth at 38 weeks or even earlier, and in many situations this is considered the norm. Moreover, if a woman is pregnant with more than one child at once, then, in most cases, she will begin to give birth earlier than the date set by the gynecologist.

It is important to understand that the baby can be born 1-2 weeks later due date– in most situations this is not considered a deviation.

That is, a deviation from the "standard" 40 weeks by 1-2 weeks forward or backward is not considered something abnormal.

It is important to understand the fact that a variety of factors can influence the duration of pregnancy and the approximate day of delivery. So, for example, to premature birth can lead to various diseases and complications.

Thus, in the absence of complications, the child is born only fully mature and ready for life outside mother's womb. It is almost impossible to accurately calculate the date of birth. But to establish the estimated or approximate date of birth will help you the above ways, as well as our online due date calculator.

Health to you and your baby!

Pregnancy is a long-awaited and desired event for many women. And now it will be interesting for you to find out everything about your situation: how pregnancy develops by weeks, what happens in the body. And it is with the help of the pregnancy calendar that you can do this very quickly and easily.

Pregnancy Calendar is a convenient and useful service for future parents of moms and dads, which will tell you in great detail about pregnancy by weeks. He can be your companion throughout the entire period of pregnancy up to the birth itself.

Pregnancy is divided into 3 trimesters:

  1. First trimester - 1-13 weeks after conception
  2. Second trimester - 14-26 weeks
  3. Third trimester - 27-40 weeks

How does the fetus develop during each trimester? Our pregnancy calendar will give you the answer.

Why you need a pregnancy calendar

The pregnancy calendar will tell expectant mothers about how their baby changes and grows at one time or another, how its organs develop, how the baby gains weight. Our pregnancy calendar will tell you what to do and what to abstain from at each stage of pregnancy, which doctors to visit, how to eat and what lifestyle to lead so that your baby is born healthy.

Also, our online pregnancy calendar will help you find out in which week with the help of ultrasound you can determine the girl you have to be born or the boy.

It is this weekly pregnancy calendar that gynecologists use when determining the age and development of the fetus. But there is also the age of the fetus, which differs from the menstrual period of pregnancy by 2 weeks.

In addition, this online pregnancy calendar allows expectant mothers to communicate and share their feelings and impressions with friends in an interesting position every week of pregnancy. Leave your comments and you will find out who has the same feelings and what they can mean.

But you need to know that the body of each pregnant woman is different, and our calendar does not take into account individual characteristics menstrual cycle, so the calendar contains information common to all. All dates are approximate, as the length of the menstrual cycle varies from woman to woman and can vary, as a rule, from 24 to 36 days. In addition, you need to take into account the fact that the cycle may be irregular.

Reviews

Galina Chalay
I approached the moment of conception very consciously and, of course, I take my pregnancy responsibly. It is very important for me to know what happens to the baby at each stage of his development. After all, from the moment of conception, he is my child, whom I must take care of. Therefore, I always look with pleasure at the pregnancy calendar and read how my son lives in my tummy.

Natalia Semerichko
For me, the most important thing was that by reading about my week of pregnancy, I could chat on the forum and discuss feelings with other expectant mothers who are at the same time.

Maria Krylova
This calendar helped me learn a lot about my future baby. useful information. During this period, I was most interested in how he was in my tummy. After all, this was my first pregnancy. Very convenient and helpful service. Thank you very much!

Send your feedback about the Pregnancy Calendar to editorial@site

Why should a pregnant woman and a doctor know what the gestational age is? Firstly, to determine the term of childbirth, secondly, to adequately monitor the development of the baby, correcting possible developmental delays in time, and thirdly, to determine the term for maternity leave.
I want to make a reservation right away that there are obstetric and true timing pregnancy. Obstetricians begin to count the gestational age from 1 day of the last menstruation. This is quite justified, because from that moment the egg begins to mature, which the sperm will later fertilize, the zygote is formed and implanted in the uterus, the fetal egg with the embryo and then the fetus (after 12 weeks of pregnancy) will begin to develop. The duration of pregnancy from the first day of the last menstruation to delivery is about 10 lunar months or 280 days or 40 weeks. However, each fruit has its own period prenatal development- from 37 to 42 weeks. It depends on many factors, but primarily due to genetics. It is necessary to ask at what gestational age the patient herself, the father of the child, was born, until what period the maternal relatives carried the pregnancy.
The true gestational age is two weeks behind the obstetric one - it is counted from the day of ovulation and conception. Thus, to determine obstetric term pregnancy to the true need to add two weeks.

How to find out the gestational age by ovulation and the date of conception

Ovulation is the very period of the menstrual cycle when the conception of a child can occur. During ovulation, a woman's ovary fallopian tube a mature egg comes out and “waits” for spermatozoa there. Unprotected intercourse at such a time in more or less healthy woman and men are more likely to lead to pregnancy. According to the date of ovulation, the gestational age is determined.
A woman ovulates around the middle of her menstrual cycle (but not every month). If your menstrual cycle is 28 days, then ovulation will occur somewhere on the 14th day, with a 35-day menstrual cycle - on the 17-18th day of the cycle. Exact term pregnancy should be counted starting from the day of ovulation.
Ovulation can also be determined at home, using special tests sold in almost any pharmacy, or by regularly measuring basal body temperature(temperature in the rectum). For the entire first half of the cycle, it will stay at about the same level - below 37 degrees. The day before ovulation will decrease slightly. And on the day of ovulation and on all subsequent days, you will stay at the level of 37-37.2 degrees. Thus, you can calculate the gestational age () if it began on the menstrual cycle when you determined ovulation.
There are women who can determine their ovulation without any tests and temperature measurements, just by subjective feelings- pain in the lower abdomen, increased libido, increased amount of vaginal discharge. It is not difficult for such sensitive women to determine the gestational age on their own.
The most accurate way to determine the gestational age by the date of ovulation is an ultrasound. This is the only way to accurately see ovulation. Only now it is problematic for a week, or even longer, to go for an ultrasound scan every day. Yes, and materially such "pleasure" will not be available to every woman. Trying to determine your ovulation only so that later you can accurately calculate the gestational age is inappropriate. There are more simple ways calculating the gestational age already, in fact, after the onset of an interesting situation.

From the first date of the last menstruation count the number of days (weeks) at the time of examination of the pregnant woman. To determine the day of birth, 280 days (10 lunar months) are added to the first day of the last menstruation or the Negele formula is used: 3 months are subtracted from the date of the start of the last menstruation and 7 days are added. Similar Method cannot be used in women with irregular menstrual cycles.


Determining the gestational age by gynecological examination.

If you came for an examination to a gynecologist in the first weeks of pregnancy (at 3-4 weeks), then it will not be difficult for the doctor to accurately determine the gestational age. IN this case produced based on the size of the uterus. For example, at 4 weeks pregnant, the size of the uterus can be compared to chicken egg, at 8 weeks - with a goose egg. An experienced gynecologist is able to determine the gestational age by vaginal examination with an accuracy of one day. Pregnancy beyond 8-12 weeks is difficult to pinpoint just based on the size of the uterus. Since starting from the second trimester of pregnancy in women who are at the same gestational age, the size of the uterus may differ.

Determining the gestational age by ultrasound.

Of course, here, as in the previous method, much depends on the qualifications of the doctor who interprets the results. Ultrasound data obtained before the 12th week of pregnancy are considered the most correct for determining the date of the expected birth. At this time, the determination of the gestational age is based on the measurement gestational sac, its average internal diameter.
In the second and third trimesters, the gestational age is determined based on the determination of such parameters as the circumference of the fetal head, the average diameter chest and fetal tummy, fetal tummy circumference. The most reliable is the information obtained by measuring the circumference of the baby's head.
However, in general it is believed that late dates pregnancy error in determining the term using ultrasound increases. This is understandable: after all, each child develops individually, and at the end of pregnancy, the size of the fetus, which the doctor focuses on in his calculations, can vary significantly depending on the characteristics of a particular child.
With all the variety of methods for determining the term upcoming birth, there is no one “perfectly accurate”, as we have already said. Therefore, we can say that more or less precise definition the term of the upcoming birth is possible if all the data obtained are not contradictory, but complement and reinforce each other.
Although even in this case, the date of delivery can be shifted by one to two weeks in one direction or another due to the fact that urgent delivery (that is, delivery on time) can occur between 38 and 42 weeks of pregnancy.

Determining the gestational age by the first movement.

Primiparous women begin to feel the first movements of the baby at a gestational age of 20 weeks. Multiparous a little earlier - at 18 weeks. Gynecologists recommend that a woman remember the date of the first movement and be sure to enter it in the dispensary card of a pregnant woman. When setting the term of pregnancy and childbirth, this has great value. For example, in order to determine the date of childbirth, it is necessary to add 20 weeks (or 4.5 months) to the date of the first movement, for multiparous women, it is necessary to add 18 weeks or 5 months.
But this method of determining the gestational age is not always correct. There are women who, even in their first pregnancy, feel the movements of the baby much earlier. due date at 20 weeks, at 17 weeks, or even earlier. Especially often such early movements are observed in thin women. There are women who feel the first movements 2 weeks later than the due date.
Doctors about such early movements and setting the gestational age on their basis, there is an opinion. Most experts believe that women do not feel the baby’s movements ahead of time, but the “work” of the intestines. After all, as you know, most pregnant women suffer from increased gas formation ...

Determination of gestational age by measuring the length of the uterus and fetus.

You can calculate the gestational age in a complicated way. Only a gynecologist can make such a calculation. You are unlikely to succeed on your own. So, in order to measure the length of the uterus, the woman lies down on the couch and straightens her legs. Must be emptied first bladder, otherwise there may be errors in the determination right time pregnancy. The length of the uterus is measured using a centimeter tape or pelvis. Usually the length of the uterus is equal to the number of weeks. For example, the length of the uterus is 36 cm, which means that the gestational age is also 36 weeks.