Future mother 

Pregnancy calendar desired. Calculation of gestational age, methods for determining the period by week, calculator

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 delivery, it is enough to know just one date: the day of the start last menstrual period. 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 the actual gestational age. 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.

The pregnancy calculator allows you to calculate exact date and find out what week of pregnancy you are currently in, as well as the expected date of delivery. To calculate, select the date of the first day of your last period at the top of the calculator and click on the "Calculate" button. The calculator will then automatically display your current week pregnancy and expected due date.

For each week of pregnancy, two exact dates are displayed: the start day and the end day. The interval between them is exactly 7 days. You can scroll through the weeks of pregnancy using the arrows. The full list of weeks from 1st to 40th is at the very bottom of the calculator. By clicking on them, you can also flip the slider to desired week. The trimester of pregnancy to which each week belongs is indicated by Roman numerals at the bottom (near the slider) and in the upper right corner of the cells (in complete list weeks). Also, the trimesters are marked in pink, orange and blue, respectively. In general, the very concept of pregnancy trimesters is rather arbitrary and their boundaries are not clearly defined. We took as a basis the most common classification, in which the second trimester begins at the 14th week and ends at the 28th. Only your obstetrician-gynecologist can calculate trimesters more accurately after an ultrasound scan.

In the images you can see a rough illustration of the development of the baby inside the womb for each week. To the left of the images is short description fetal growth for a given week. For more complete and detailed information, you can find by clicking on the "More" link, which is located under each description.

Method for calculating the gestational age


The calculator calculates the so-called "obstetric" gestational age. It differs from the actual date by about two weeks. This method calculation is used in gynecology, because it is very difficult to calculate the exact day of conception. Therefore, the calculation is based on the first day of the last menstruation, the date of which, as a rule, every woman remembers. 280 days or 40 weeks are added to this day. Thus, the first two weeks of the obstetric period you are not yet pregnant, because. ovulation has not yet occurred (based on an average menstrual cycle of 28 days). This method is not completely accurate because some women ovulate late or early. But, in general, for most expectant mothers, such a calculation turns out to be quite accurate.

In any case, we draw your attention to the fact that the pregnancy calculator allows you to calculate the term using the most general formula, which does not take into account individual characteristics your body. It cannot be used for self diagnosis or any other medical purposes, since the results of its calculations are for informational purposes only. by all precise calculations and any other manipulations should only be handled by your doctor.

Any woman preparing to become a mother looks forward to the appearance of two cherished stripes on the test. After this moment, excitement and anxiety arise. Is the baby developing normally when you need to go for the first ultrasound, and, finally, when is the birth coming? All these questions can be answered by knowing the exact gestational age.

What is the gestational age?

Very often, confusion in the head of a pregnant woman arises from a misunderstanding of this term. Therefore, it is important to know when the development of the embryo begins, and when the countdown to birth begins.

The egg after ovulation (exit from the ovary) lives for about a day. It is this time that is considered the most favorable for conception. With a menstrual cycle of 28 days, ovulation occurs on the 14th day. At the moment of fertilization, the sperm fuses with the egg, and after a week developing embryo attached to the inner lining of the uterus.

Since in most women the length of the menstrual cycle is inconsistent, then the exact date ovulation and conception no one knows. Therefore, all obstetricians in the world are considered to be the beginning of pregnancy on the first day of the last menstruation. After 9 months (280 days) after this day, childbirth should take place. This is the paradox: the countdown of pregnancy has already begun, but conception has not yet occurred. Therefore, the life span of the embryo less time Pregnancy averages 2 weeks.

Methods for determining the gestational age and date of birth

All doctors in the world determine the duration of pregnancy by one main parameter (ultrasound) and two auxiliary ones (date of menstruation and examination of the pregnant woman).

ultrasound

The main method is ultrasonography. It is important to remember that the accuracy of this method is maximum in the first 10-12 weeks, and then it drops. Therefore, it is ultrasound of the first trimester that is widely used to determine the expected date of birth.

Modern devices can determine fertilized egg in the uterus from 3-5 weeks of pregnancy. As the embryo grows to 3-4 mm, it becomes possible to measure its KTP (coccyx-parietal size), which serves as the basis for determining the gestational age to the nearest day. Usually, in the conclusion, the doctor indicates which period he means: obstetric (from the last menstruation) or embryonic (from the moment of conception).

After 22 weeks of pregnancy, it is impossible to accurately determine the age of the fetus. But the measurement of its main parameters (head size, length femur, abdominal circumference) allows you to evaluate the dynamics of growth. If it does not correspond to the period declared during ultrasound in the 1st trimester, then there is a possibility of fetal growth retardation syndrome. In addition, there are individual hereditary characteristics ( short stature, large head), due to which in the third trimester the gestational age is not subject to calculation by ultrasound.

Date of the last menstruation - calculation calculator

Determining the gestational age by the day of the last menstruation is the most affordable way for a woman. If the expectant mother is a happy owner of a regular cycle of 28 days, then she can independently and fairly accurately calculate the date of birth. There are special Naegele formulas for this.

PDR \u003d LMP - 3 months + 7 days

  • EDD - estimated date of birth
  • LMP - first day of last menstrual period

For example, if the LAP was on June 15th, then PDR = June 15th - 3 months + 7 days = March 15th + 7 days = March 21st. This is the basis for determining the date of birth in all special calculators for calculating the gestational age.

Gestational age is determined by adding to the LMP the number of weeks that have passed since that day. Therefore, every woman can calculate the gestational age using a regular calendar.

When is it impossible to determine the period for menstruation?

  • Irregular menstrual cycle . With a cycle greater than 35 days, ovulation does not occur on the 14th day. Therefore, the Negele formula will give an inaccurate result (see).
  • Reception contraceptives . In case of non-compliance with the regular intake oral contraceptives pregnancy may occur. Due to sudden ovulation, the formula for calculating the EDD is also not suitable (see).
  • With the threat of termination of pregnancy early dates . It happens that there is a threat of termination of pregnancy at the shortest possible time. Very often it manifests itself as scarce spotting on the days corresponding to the expected menstruation. That is, a woman can confuse bleeding at the 5th week of pregnancy and regular menstruation, and will not even guess about her interesting position. In such cases, the period is determined using ultrasound.

Examination of a pregnant woman

Registration of each pregnant woman in women's consultation starts with an inspection. Determining the size of the uterus and the height of its bottom (that is, the upper part) can provide indicative information about the gestational age. This method is not 100% accurate. After all, the individual location of the uterus, fibroids and complete bladder may make inspection difficult. A multiple pregnancy is associated with a large increase in this body.

HCG level

Already 8-10 days after conception in the blood future mother the B-subunit of hCG is determined. This hormone appears during pregnancy and doubles every 2-3 days (see). It is possible to judge the gestational age by its level only indirectly.

  • Firstly, hCG norms for each week of pregnancy have a large range.
  • Secondly, its level increases with multiple pregnancy and some fetal anomalies. Therefore, it makes no sense to focus on this hormone when calculating the gestational age by week, when more are available. precise methods(ultrasound, for example).

Date of first movement

It is believed that nulliparous women feel fetal movements from the 20th week of pregnancy. Multiparous can feel them already from 16-18 weeks. In fact, it all depends on the individual characteristics of the mother and child, the thickness of the fat layer on the belly of the pregnant woman and on her desire to feel the tremors. In addition, intestinal peristalsis is often taken as the first movement. Therefore, you should not rely on this indicator in calculating the gestational age.

How to determine the gestational age during IVF?

With in vitro fertilization, many women doubt how to correctly count the weeks of pregnancy. After all, an already developing embryo is planted in the uterine cavity. But regardless of the method of fertilization ( naturally, sperm insemination or IVF) the gestational age is determined from the first day of the last menstruation. The only exception can be considered IVF with a menstrual suppression protocol (superlong protocol). In this case, the period is counted from the day of embryo transfer with the addition of two weeks.

Why do doctors determine the exact gestational age?

  • To assess the rate of fetal development
  • To determine the date of birth
  • For screening for chromosomal mutations (Down syndrome, etc.)
  • To determine the viability of a child in preterm birth

The main goal of determining the gestational age for the expectant mother is to tune in to the upcoming birth of the baby and get acquainted with information about intrauterine development by weeks.

Our online calculator pregnancy will help you calculate your pregnancy by week. Pregnancy is an amazing period in the life of any woman, when inside appears and develops new life. This is happening at a fairly fast pace. In 9 months, the fetus goes through stages of development from a few small cells to an organized organism. With each week of pregnancy, the little one undergoes certain changes, improves existing systems, acquiring new qualities. Because future mother very interesting throughout interesting position find out what's new happens to the baby, what he is like, what's on this stage can do. Description next.

How to calculate the gestational age by week

For this, an interactive Pregnancy Calculator is intended, which allows you to calculate a woman’s pregnancy by weeks, find out in this way approximate date the birth of a child. The calculation is carried out from the first day of the last menstruation, although it is more correct to consider the term of conception from ovulation. Although the exact time of ovulation is not always known, the pregnancy calculator reflects the timing for the more common cycle of 28 days. With a long or short cycle, amendments are possible, although in practice it is customary to calculate the gestational age of a woman by menstruation. This Pregnancy Calendar is designed to calculate the timing of key moments in fetal development and includes a birth calculator.

What is gestational age and how is it calculated? It is customary to single out obstetric and embryonic terms, and many mothers simply get confused in these terms, and today we will try to figure it out.

The first thing we will start with is the obstetric term, because in fact, our gynecologist will make all calculations based on the obstetric term.

obstetric term
The obstetric period is calculated from the first day of the last menstruation, so when you go to the gynecologist for the first time, clearly know the date of your last menstruation, this will make your life easier, and in the future all of your data will be entered in a special card, everything will be written there.
The obstetric period involves 280 days of pregnancy, well, these are averages, it is clear that each mother is an individual and this period may vary, but it is customary to consider 280 days.
According to the obstetric period, they issue directions for tests, a certificate of maternity leave and all other documents that you will need in the future, tighter exchange card, there all data will be put on the basis of the obstetric term.
And according to the obstetric term, the estimated date of birth is calculated, this is the PDR.

How to calculate the expected due date

The first day of the last menstruation, 3 months ago and 7 days are added, so you can calculate your gestational age and when your baby will be born.

Embryonic term
It is calculated from the moment of conception and is usually shorter by 14-15 days of the obstetric period.
That is, in fact, we all know biology, menstruation has passed and a new cycle of egg formation has begun, and on day 14-15, on average, it matures and is ready for fertilization, this is called the day of ovulation.
In fact, it will be very difficult for us to determine and calculate the exact day of ovulation, of course there is different tests in a pharmacy, you can buy and know exactly when you ovulate,
but in principle it is very difficult to determine or calculate, because fertilization itself occurs on the day of ovulation, plus or minus 3-5 days.



The need to calculate the gestational age by weeks occurs in almost every pregnant woman and more than once during pregnancy. And this is necessary not only in order to simply know your due date or correctly track the pregnancy calendar. I also want to calculate the duration of pregnancy and childbirth in order not to doubt the correctness of the doctor’s actions, if they make a mistake in the consultation - this can also affect the date of going on maternity leave, you don’t want to work an extra couple of weeks, right?

First, some general information.

Our calculator will help you calculate the obstetric gestational age, it is slightly inconsistent real term fetal life. Gynecologists build all their calculations on the date of the first day of the last menstruation, and do not count from fertilization, this is due to the ease of error in the date of conception.

Ovulation in a woman can significantly shift in time, especially if she does not have a regular cycle, and of course, not everyone can know the exact date of fertilization, it is difficult to calculate the gestational age by ovulation. And the date of the beginning of the last menstruation, as a rule, is known.

We have a special calculator that allows you to independently calculate the gestational age online. It will give you information not only about obstetric period pregnancy, but also the date of conception, the age of the fetus, the date of delivery.

The problem may arise if yours is not regular. How to correctly calculate the gestational age by menstruation with an irregular cycle? You need to add the length of the last 6 cycles and divide by 6, so you get average duration, this is the number of days and must be entered in the calculator field.

All data obtained can be easily controlled using other calculation systems.

You can accurately calculate the gestational age (well, or relatively accurately, as gynecologists think) using the Negele formula. It does not take into account the length of your cycle and therefore the result may differ from the period that our calculator gives, but this will certainly coincide with the calculations of the gynecologist: we subtract 3 months from the first day of the delay in menstruation and add 7 days to the date obtained. This is your due date. Calculate the gestational age by months, weeks and days, as with our calculator, using this formula will not work.

If you had an ultrasound, the doctor measured the development of the baby. Its weight, the length of the bones make it possible to calculate the gestational age by ultrasound, but this calculation is accurate only in the first trimester, the longer the period, the more difference V physical development in different children, and there is a higher risk of error in determining the timing of pregnancy.

Almost all calculation methods carry a certain risk of error, which is why only 4% of children are born on the PDR (preliminary date of birth).

It is better to evaluate the results of calculations in a complex (ultrasound, date of the last menstruation, first movement and other dates and signs). And still, the date of birth can fall between 37 and 42 weeks of pregnancy.