Calculate the due date based on the last day of your period. Estimated due date calculator

The duration of pregnancy from conception to birth of the child is about 266 days, or 38 weeks. Since the date of conception is usually unknown with certainty, in modern obstetrics it is customary to calculate the gestational age from the first day of the last menstruation. With this calculation, it is approximately 280 days, or 40 weeks, since ovulation (the release of a mature egg from the ovaries) and, accordingly, fertilization usually occurs approximately two weeks after the start of menstruation. When turning to an obstetrician-gynecologist, many expectant mothers begin to worry about the difference in the date of birth - the one calculated by the doctor and the one expected by the woman herself. In order not to worry in vain, you need to know that there are two stages of pregnancy - obstetric and embryonic.

Embryonic term- this is the true gestational age from conception; it usually lags behind the obstetric one by about 2 weeks.

Obstetric term Doctors determine from the first day of the last menstruation before pregnancy. It should be remembered that all doctors use it: the size of the fetus, the timing of examinations, maternity leave and the date of birth are calculated taking into account only the obstetric gestational age. It is also very important to know the exact gestational age for conducting screening tests for the presence of genetic abnormalities in the fetus (ultrasound and blood tests), since these examinations are carried out at strictly defined periods of pregnancy.

During the first visits to the antenatal clinic, the obstetrician-gynecologist usually determines the expected date of birth (ED). Several methods are used for this.

Method 1. Method for determining the date of birth based on the date of the last menstruation

This is the most common method of calculating the maximum allowance. To calculate the date of birth, three months must be subtracted from the date of the last menstruation. You need to add 7 days to the resulting date - this number is the expected date of birth. Obstetricians-gynecologists, when calculating PDR using this method, usually use special obstetric calendars, which greatly simplify the calculations.

However, it is not always possible to accurately calculate the MDR using this method alone. This happens in cases where a woman has irregular menstruation, or in those patients who have a regular but long menstrual cycle. For example, if a woman has a normal cycle length of 35 days (and not 26-28, as for most), then, most likely, she will be able to conceive only around the 21st day of the cycle (and not on the 14th, as with a 28-day cycle). Accordingly, the PDA calculated by menstruation will be a week earlier than the actual expected date of birth.

Method 2. about the date of ovulation or date of conception

If the date of conception is reliably known, then you can calculate the expected date of birth yourself by adding 266 days - this is the average gestation period. But there are some nuances here too. You need to understand that even if a woman knows exactly the date of ovulation or the date of sexual intercourse after which pregnancy occurred, this does not mean that she absolutely knows the date of conception. A sperm that enters a woman’s body is capable of fertilization on average within 4–5 days, sometimes even within a week, and a mature egg retains the ability to conceive within 2 days after ovulation. Therefore, even knowing exactly the date of sexual intercourse or ovulation, one cannot say with certainty that fertilization occurred on that day. It could have happened later. Therefore, the period calculated from ovulation or the date of conception cannot be considered absolutely accurate.

Method 3. Method for determining the due dateupon first appearance at the antenatal clinic

Typically, the date of the upcoming birth and the gestational age are calculated by the doctor when registering for pregnancy. Doctors call this calculation method “by first appearance at the antenatal clinic.” The duration of pregnancy, and, accordingly, the date of birth in this case is determined by the following parameters - the size of the uterus and the level of human chorionic gonadotropin in the blood. When examining a woman in a gynecological chair, an obstetrician-gynecologist determines the size of the uterus with both hands. This method “works” most accurately in the early stages of pregnancy, up to about 12 weeks. The earliest period that can be determined by the size of the uterus is 5 weeks of pregnancy. By this time, the uterus is slightly enlarged, softens and becomes rounded. At later stages, the size of the uterus may vary slightly depending on the size of the fetus, the amount of amniotic fluid, and the structure of the woman’s pelvis.

A blood test for hCG (human chorionic gonadotropin) helps determine the gestational age and calculate the approximate date of birth in the early stages. It begins to be produced in the body of the expectant mother with the onset of pregnancy, and gradually, until about the 11th week of pregnancy, its amount increases and then decreases slightly. Determining the concentration of hCG in the blood at the beginning of pregnancy helps to accurately determine its duration. Having received the results of a blood test for hCG, it is worth paying attention that in laboratory tables, which determine the correspondence of the hormone level to the gestational age, the embryonic period is often indicated. That is, to determine the usual obstetric gestational age, 2 weeks should be added to the result obtained.

Method 4. Method for determining the due date about ultrasound

When performing an ultrasound in the early stages of pregnancy, measuring the size of the fertilized egg and embryo, the gestational age can be determined with great accuracy. At 4–5 weeks, an ultrasound examination reveals a small “black circle” in the uterus - this is the fertilized egg, in which the embryo will appear a little later. At about 6–7 weeks, the embryo appears in the form of a small “stripe” and its heartbeat can be seen. The term calculated by measuring the CTE of the embryo is considered more accurate (CTE is the coccygeal-parietal size, that is, the maximum distance from the fetal head to its tailbone). After 12 weeks, the gestational age is determined by ultrasound by measuring the various sizes of the head and abdomen of the fetus, the length of its arms, legs, etc.

Until 9–10 weeks of pregnancy, the embryo grows proportionally, and its size in all women with the same gestational age will be approximately identical. In the future, these indicators will differ for expectant mothers of different nationalities, with different body weights, the weight of mom and dad at birth will also matter, and so on. That is, in later stages of pregnancy, normally developing children of the same “age” can have different sizes (fluctuations can be about 2 weeks and sometimes even more), and in such a situation, the gestational age cannot be reliably determined by ultrasound data.

Method 5. Method for determining the due dateabout the first movement of the fetus

Let us note right away that this method of determining PDR has recently been used less and less. It is based on the fact that women carrying their first child begin to feel its first movements on average at about 20 weeks of pregnancy, and those pregnant for the second or more times - a little earlier, at 18 weeks. That is why obstetrician-gynecologists recommend that the expectant mother remember the date of the first movement of the fetus and enter this data into the exchange card. To calculate the expected date of birth for women preparing to become a mother for the first time, 20 weeks must be added to the date of the first fetal movement, and for women expecting a second baby - 22 weeks.

However, this method of determining the date of the upcoming birth is often erroneous. What's the matter? The problem is that the time when a woman can feel the first movements of the fetus is very individual and depends on her sensitivity, body type, as well as employment and experience. So, some expectant mothers feel the first movements already at 15-16 weeks, and some only after 20. Slender women, as a rule, begin to feel them earlier than plump ones. Expectant mothers who lead an active lifestyle and work a lot usually feel fetal movements later than those who are less busy and have more opportunities to listen to their inner feelings. Pregnant women for the second or more times already know exactly how the baby’s movements are felt, therefore, as a rule, they recognize the baby’s movements earlier than “inexperienced” first-time women, who often mistake fetal movements for increased intestinal motility and gases.

All of the methods described above allow you to calculate the expected date of birth. However, we must remember that, of course, it is not absolutely accurate. Prematurity or miscarriage is common. The onset of premature labor can be triggered by abnormal development of the fetus, pathological processes in the body of the expectant mother, stressful situations, hereditary factors and many other reasons. Therefore, it is very important to realize that calculating the date of birth is a very conditional concept, regardless of the method used, and it is not possible to predict exactly when the baby will be born.

How is the expected due date calculated during IVF?

In the case of IVF (in vitro fertilization), fertilization of an egg with a sperm is carried out “in vitro” by an embryologist. Embryos develop in the laboratory for 3–5 days, after which they are transferred to the uterus. Doctors calculate the true gestational age following IVF from the date of ovarian puncture, that is, a procedure in which follicular fluid and the follicles contained in it are taken with a special needle for subsequent in vitro fertilization, and 2 weeks are added to determine the “usual” obstetric period. to the date of ovarian puncture.

If the transfer of the embryo into the uterus was preceded by its cryopreservation (that is, freezing in liquid nitrogen), to determine the exact gestational age, doctors add 5 days to the transfer date (this is the number of days of embryo development before freezing), and to determine the obstetric period, add 2 to the resulting true gestational age. weeks and calculate the due date.

Pregnancy is one of the most exciting and at the same time responsible periods in the life of every woman, and therefore it is not at all surprising that each of us wants to know the date of birth as soon as possible. However, this issue often causes numerous disagreements and disputes. Expectant mothers “torture” doctors with their questions, because they want to prepare for an important event, but they just shrug their shoulders, because they are not able to accurately determine the date of birth of the long-awaited baby.
In order to Calculate the due date, click the “find out due date” button.

Today: 04.11.2019
Date of the first day of last menstruation:
Conception most likely occurred (+-2 days):

Estimated due date:
Time left before giving birth:

The estimated date of birth (EDD) is calculated in several ways, each of which is approximate. That is, if according to calculations the baby should be born on January 1, then it is not a fact that this will happen with one hundred percent accuracy on this very day. Very often there are deviations from the expected date in one direction or another. And labor can begin either 2 weeks earlier or later. I bring to your attention a fairly simple, but very effective way to find out the probable due date of a child, which has been successfully used by many doctors in clinics for quite a long time.

Calculation based on the last day of menstruation

So, to independently calculate gestational age and using it to determine the expected day of birth, you need to remember the start date of the last menstruation. It is on this basis that all calculations are made. From this date you need to subtract 3 months and add another 7 days to the result.
The resulting number will be the expected due date of your long-awaited baby.
For example, the date of the last menstruation is April 22. This means that 3 months must be subtracted from this date.

We take away and receive - January 22. We add another 7 days to this figure and get January 29 - this day will be the expected date of birth.

It is worth noting that this method of calculation is best suited for women with a regular menstrual cycle, which lasts 28 days.
4 Alternative Ways to Calculate Due Date

1. You can find out the due date with fairly high accuracy by visiting a gynecologist’s office. The doctor will not order any tests for this, he will simply measure the size of the uterus, which will increase in size according to the age of the fetus. However, this method of calculating the date of birth of the baby is effective only in the first trimester of pregnancy. In the later stages (in the 2nd and 3rd trimester) in each woman, an increase in the size of the uterus occurs with varying intensity, depending on the individual characteristics of the body.
2. You can calculate the date of birth based on ovulation, which is the most favorable period during which conception most likely occurs. On such days, a woman usually experiences increased sexual desire. In addition, her discharge (cervical fluid) becomes stickier and thicker, basal body temperature rises by several tenths of a degree, the cervix rises, and the mammary glands become dense and painful.

3. Hardware calculation using ultrasonic waves can also be considered one of the most effective methods that allow you to determine the due date with an accuracy of 1-3 days. The most accurate calculations will be if an ultrasound is done during the 11-14 weeks of pregnancy.
4. His first movement, which usually occurs at the 20th week (for first-time mothers) and at the 18th for the second and subsequent pregnancies, will help declassify the secret of your child’s date of birth. In ancient times, when there was no ultrasound, this method of calculating the due date was almost the only one.

As soon as the expectant mother feels the first tangible tremors of her baby in her stomach, 20 weeks should be counted from that moment. The resulting date will be the probable day of birth of the child. If the birth is not the first, movements are usually felt earlier - at 18 weeks, so you will have to add not 20, but 22 weeks to this period.

The effectiveness of hardware methods in calculating the due date

Examination of the fetus in the third trimester using an ultrasound machine makes it possible to accurately determine the date of pregnancy, and therefore the expected due date. The fact is that only with the help of ultrasound diagnostics can a doctor observe the condition of the placenta, the position of the baby’s head in relation to the entrance to the pelvis, the level of opening of the cervix, signs of fetal maturity, as well as many other important factors. All these parameters are decisive in determining the readiness of the unborn baby and his mother for childbirth.

Is deviation from the deadline normal?

As mentioned above, all calculations of the expected due date are nothing more than a rough guideline that should not be relied heavily on. According to statistics, only 17% of women give birth on the appointed day, while the remaining 83% give birth either earlier or later. Thus, we can conclude that no specialist, no matter how smart and qualified he may be, is able to predict with high accuracy the date of onset of labor.
Normally, birth can occur between 38 and 42 weeks. pregnancy. The birth of a child will be neither premature nor late, but normal and physiological.
Pregnancy often goes beyond term due to complications in the first trimester. In addition, maternal inheritance should be taken into account. If your mother and grandmother gave birth much later than the due date, then most likely the same thing awaits you. Therefore, it is very important to realize that calculating the due date is a very complex, conditional and individual issue for each expectant mother.

How do the characteristics of the menstrual cycle affect the date of birth?

The duration of a woman's menstrual cycle also influences the due date. For example, if it exceeds the standard twenty-eight days, then most likely the pregnancy will last more than forty weeks, and vice versa. However, in this case, the deviation in one direction or another usually does not exceed 5 days. It is worth noting that in such calculations errors are often made, since very often normal bleeding that opens after fertilization of the egg is mistaken for menstruation.

The article describes all the available ways to independently determine the date of your upcoming birth.

The emotional coloring of the news about expecting a baby begins to gradually lose its brightness and intensity characteristic of the first days, and you return to a more or less normal state. The first thing that usually comes to mind is to find out when the baby will be born.

This completely natural desire is due to both practical goals and simple human curiosity:

For some, the month of the year is interesting to start shopping for appropriate clothes for the baby
for some it is important to choose a name for a child according to the laws of astrology or the church calendar
for some, the expected date is needed to plan a spouse's vacation

The reasons may be different, but information about when a woman should prepare for childbirth is of interest to many expectant mothers.

Towards the end of the third trimester, women usually begin to calculate the expected date in every possible way, checking it over and over again, because they feel heaviness and fatigue, and they cannot wait to meet their baby as soon as possible.

How to correctly calculate the due date? Table

Almost every person knows that it takes nine months to bear a child. But how to count them correctly:

from what day - sexual intercourse, ovulation, conception, implantation, last menstruation?
Should we take calendar months or conventional months of 30 days, exactly how many days do they have?

When an expectant mother faces pregnancy for the first time, a period of nine months seems very uncertain, and in order to calculate the due date as close to reality as possible, you want specifics.

The generally accepted method for determining the expected date of birth (hereinafter referred to as EDA) for the purpose of monitoring fetal development and pregnancy in general is counting from the date of the start of the menstrual cycle.

PDR = date of menstruation + 280 days (or 40 weeks)

In this way, conditional boundaries of pregnancy are established, called obstetric term, which becomes a guide for doctors and expectant mothers to monitor the progress of the baby’s development. When a woman is asked how far along she is, the pregnant woman will name the obstetric week of pregnancy.

In fact, true pregnancy occurred after the date of the last menstruation by approximately two weeks, and accordingly it lasts less than the obstetric period.

Why does the medical community resort to such a strange method of counting pregnancy from the day when it is only in the plans of potential parents? To find the answer, let’s briefly consider what happens in a woman’s “pregnant” cycle and when:

regardless of when intimacy took place, fertilization or conception will occur on the day of ovulation, and taking into account the vitality of sperm, the difference between these moments can reach up to 5 days
Ovulation occurs on average 14-15 days before the end of the cycle (next menstruation), but it can occur earlier (16 days) and later (12-13 days)
Conception does not guarantee pregnancy; for this, the fertilized egg must attach to the uterus, or be implanted, which on average takes 6-8 days, but can also vary over time

IMPORTANT: 80% of cases of conception end in unsuccessful implantation, that is, pregnancy does not occur, but the woman does not even know about it, since her periods come on time.

So, it is very difficult to establish the starting point of pregnancy, due to the fact that it depends on several individual factors:

cycle duration
ovulation day
duration of implantation

Even theoretically knowing exactly the date of pregnancy, this would not guarantee one hundred percent determination of the date of birth, since the onset of labor is also determined by many factors, including:

physiological readiness of the baby
nature of pregnancy
mother's age and health status
number of previous pregnancies

For these reasons, doctors do not aim to accurately calculate the true date of conception and implantation. In addition, most women remember when they had their last menstruation, but not many people know what ovulation is and when it occurs specifically for them.

Therefore, it is much easier to count from the beginning of the cycle. This makes several assumptions:

cycle duration 28 days
Ovulation occurs after 14 days (on the 15th day)
the timing of implantation falls within the normal range

If you fit into the specified parameters, you can safely look in the table below for the date of the expected meeting with your baby. Nobody guarantees the exact probability, but this is as close as possible.

in the column on the left you should find the month in which you last had your period (indicated in black with an asterisk)
then find in the line with this month the number (indicated in black) corresponding to the start date of the last menstruation
below it will be indicated the expected date of birth and month (indicated in crimson)

Examples given in the table:

in a woman with the first day of her last menstrual period on March 28, delivery is planned for January 2
if the onset of menstruation occurred on August 11, replenishment should be expected on May 18

If your cycle is slightly different, the table will also be a good guide, but you need to be prepared for the fact that a difference of 1-2 weeks is considered normal. In other words, from the point of view of medical science, the ideal pregnancy is 40 obstetric weeks, but more often it falls in the range of 38-42 weeks.

IMPORTANT: According to the latest data, the range of variation between the duration of pregnancy is 37 days or 5 weeks. Previously, this figure was 4 weeks (=42-38).

How to calculate the due date based on ovulation?

There may be cases when a woman knows exactly the day on which she ovulated. This is usually typical for women who have been planning pregnancy for a long time.

For example, ovulation became known using:

Ultrasound, which the woman had several times during the cycle to monitor the maturation and release of the egg
an ovulation test that shows a positive result 24-36 hours before ovulation
basal temperature chart
your own obvious sensations thanks to long-term observations of your body

In these circumstances, I would like to know the MRP more accurately, especially if the cycle does not fit the ideal standards both in terms of total duration and the number of days in the second phase. The formula for calculating day “X” in this case looks like this:

EDA = ovulation date + 266 days (or 38 weeks)

This period is called embryonic. If you compare these numbers with the traditional formula described above, you get a difference of 14 days (= 280-266). Namely, on days 14-15 of the cycle, ovulation occurs in an average cycle of 28 days.

Recent research from the US National Institutes of Health has concluded that pregnancy is often 268 days from ovulation (rather than the accepted 266), that is, 38 weeks and 2 days. The length of the gestational period also depends on how long it takes for the fetus to implant into the uterus. This point in the study was recorded on the first day of hCG growth.

IMPORTANT: It has also been found that the length of pregnancy is affected by the age of the mother and her birth weight. The older the woman and the higher her birth weight, the longer the gestation period will be.

How to calculate the due date based on the date of conception?

Conception or fertilization occurs when the sperm and the egg meet. Due to the fact that the egg leaves the follicle once a month (normally), which is called ovulation, and retains the ability to create a new life for only 24-36 hours, the meeting with the sperm and conception usually occurs on the day of ovulation or the next day.

Thus, the date of conception and the date of ovulation often coincide or differ by only 1 day. In this regard, the principle of calculating the PDR based on the date of conception is similar to the method based on the date of ovulation described above.

IMPORTANT: You should distinguish between the day of sexual intercourse and the day of conception. The difference between them can reach up to 5-7 days, depending on the life expectancy of the sperm of a particular man.

How to calculate the due date accurately based on menstruation?

The estimated date of birth, which the gynecologist will announce to the woman, as mentioned above, is based on data about the last menstruation. In this case, the day the cycle begins is important, that is, the date on which the last menstruation began; the duration and end date do not play a role.

In order not to count 280 days from this date, there is a simpler way (Naegele formula):

PDR = date of menstruation - 3 months + 7 days + 1 year

Example #1:

last menstruation was from June 13 to June 19, 2015
on the expected start date of the next cycle, April 10, menstruation did not start, and the pregnancy test was positive
you should remember the date June 13 (the beginning of the last menstruation), the pregnant woman will be asked this more than once
going back 3 months, we get March 13, 2015
add 7 days, we get March 20, 2015
we add a year, we get March 20, 2016 - this is the PDR

IMPORTANT: In the formula, the three months subtracted are equivalent to 92 days, so if the sum of the days in the months preceding the month of the last menstruation is 89, 90 or 91 days, you should add not seven, but 4, 5 or 6 days, respectively.

Example #2:

start date of last menstruation – December 15, 2015
subtract three months, we get September 15, 2015
sum of days of deducted months: November (30) + October (31) + September (30) =91
therefore, we add 6 days, we get September 21
add a year, PDR – September 21, 2016

Example #3:

date of menstruation – May 2, 2015
minus three months – February 2
sum of days in April, March and February (not leap year) – 89
so we add 4 days to the result
as a result, PDR - February 6, 2016

How to calculate the due date with an irregular cycle?

The calculation of the date of birth used in medical practice is based on the assumption that a woman has a standard cycle with a duration of 28 days, in which ovulation occurs on days 14-15.

Let's imagine the situation:

the date of a woman’s last menstruation is September 12, the maximum period for menstruation is June 19 (September 12 +280 days)
Day X comes, labor does not begin, the woman begins to worry, and the gynecologist insists on inducing labor, threatening the aging of the placenta
and only in rare cases will the doctor ask about the length of her menstrual cycle
Meanwhile, the expectant mother’s cycle is 40 days, which means that the due date, for objective reasons, shifts by at least 12 days
Ovulation most likely occurred not on the 14th day, but on the 26th day (=40-14)

IMPORTANT: Usually the duration of the second phase of the cycle is stable and is 14 days, that is, ovulation occurs 14 days before the end of the cycle.

in other words, conception occurred 12 days later than in the standard cycle (=26-14)
accordingly, the woman is not yet “over-nursing”, the duration of her true pregnancy has not yet reached 266 days, there is no reason for concern

Thus, it is quite natural that labor has not yet occurred, and the explanation for this is logical: the woman experienced late ovulation.

If you are the owner of a non-standard or irregular cycle (more or less than 28 days), it is better to focus on the date of ovulation and count from it (add 266 (268) days to the date of ovulation). If your ovulation date is unknown, you should:

find the difference between the number of days in your cycle and the standard
if the cycle is more than 28 days, add the difference to the maximum allowance calculated from menstruation
if the cycle is less than 28 days, subtract the difference from the MRP calculated by menstruation

In the example above:

the difference is 12 days =40-28
cycle more than 28 days
therefore, the more likely due date is July 01 (= June 19+12 days)

How to correctly calculate the due date using the first ultrasound?

To obtain more accurate results, ultrasound should be performed in the first trimester. If you go too early, at 4-5 weeks, that is, immediately after the delay, there is no guarantee that the doctor will even see the fertilized egg. Therefore, if there is no threat of ectopic pregnancy, you can sign up for an ultrasound after 6-7 weeks, or better yet, from 10 to 14 weeks.

Using an ultrasound, the doctor will assess the coccygeal-parietal size of the fetus, which can be used to determine the gestational age.

For example, if the fetal CTE is 44 mm, the gestational age according to ultrasound is 11 weeks and 2 days (or 79 days).

The table indicates the obstetric period. Accordingly, there are 201 days left (=280-79) or 28 weeks and 5 days until the birth.

In the 2nd and 3rd trimester, the accuracy of the correspondence of the fetal parameters to the gestational age is significantly reduced, since the unborn baby begins to gain weight, grow and develop according to individual and genetic characteristics, which cannot be adjusted to any table.

How to calculate the due date after IVF?

Regardless of how conception occurred: naturally or in a laboratory setting, the gynecologist will still focus on PDR based on the date of the last menstruation
However, it is possible to calculate the embryonic period. The day of ovulation is taken to be the day of puncture, when follicular fluid with eggs was taken from the woman. You can add 266 days to this date and get a traffic permit
The same result can be obtained by adding 14 days to the puncture date, that is, conditionally determining the date of the last menstruation from which the obstetric period will be calculated, and counting 40 weeks (280 days)

How to calculate the due date based on the first fetal movement?

Fetal movement, although quite specific and real, is a subjective factor for determining the date of birth.

The fact is that it is very difficult to determine when the expectant mother clearly experienced the presence of a little man inside by his kicks and movements. First-time mothers notice this later than more experienced mothers, often confuse it with processes occurring in the intestines, and invent something that they cannot yet feel.

However, as a guideline, this method can be taken into account. For this:

20-22 weeks are added to the period when a primiparous woman first felt movement
24 weeks are added to the date of the first tremors felt by a multiparous woman

The different periods are explained by the fact that the former feel movements only at 18-20 weeks, and the latter - from 16 weeks.

But this method can only roughly estimate the period of labor. At what point a woman detects the first movement depends on the structural features of the uterus, on the method of attachment of the fetus to the wall of the uterus, on the woman’s sensitivity and many other factors.

How to correctly calculate the date of the second birth?

There is an observation that each subsequent pregnancy is shorter and easier than the previous one. This is not always the case and depends on individual characteristics. But often the second birth occurs earlier, at 38 weeks, while the first - on average at 39-40 weeks. Otherwise, calculating the maximum age limit is similar to the principle of determining the date of the first birth.

It is known that the main reference point for calculating the PDR is the last menstruation, but there are frequent cases when a woman becomes pregnant again with a cycle that has not yet resumed after the first birth
What to do in this case? A woman does not know the date of her last period simply because she has not yet had one after her first pregnancy.
In such circumstances, the deadline is usually determined by the results of the ultrasound. This is the single most accurate way to determine the gestational age and calculate the due date. But it must be done no later than the 1st trimester

How to determine the exact date of birth yourself: tips and reviews

If the menstrual cycle is 28-30 days, then the date of birth calculated in the antenatal clinic (for menstruation) will be closest to the truth
If the cycle differs significantly in duration from the standard or fluctuates from time to time by more than 3-4 days, inform the gynecologist about this when registering
In this case, keep in mind that labor may begin earlier or later than your MDA by the number of days your cycle is shorter or longer than the standard 28-day cycle.
You shouldn’t get too hung up on calculating the due date; the percentage of accurate hits is still not high
Prepare mentally in advance that childbirth may occur earlier or later than the due date
If the first birth occurred exactly in the PDR, this does not mean that the same will be the case with the second
Remember that PDR is primarily needed for medical purposes: identifying significant deviations in fetal development depending on the duration of pregnancy, assessing the maturity of the placenta and monitoring other vital signs in order to timely hospitalize the woman and stimulate delivery if necessary

Video: How to determine the due date?

If the delay in menstruation is slight and there are no complaints about poor health, then there is no need to rush to an appointment at the antenatal clinic yet. But your inner feeling already tells you that a miracle has happened and that you will soon become happy parents of a wonderful baby. Any woman in this position strives to get an answer to the question: when exactly is the time for childbirth? Our service allows you to determine the exact date of birth of your unborn child in a matter of minutes.

Calculate due date online

Any method of calculating the date of expected birth is based on an idea of the normal duration of pregnancy, which usually lasts about forty weeks (in some cases, a deviation of several weeks is also not a pathology). The starting point is the beginning of the last menstrual period, and it is likely that the expected event will occur after exactly 280 days or 40 obstetric weeks.

Using the online calculator presented on the website, you can easily and simply find out the likely date of your upcoming birth. All that is required of you is to enter the necessary data into the appropriate windows of the calculator, and the necessary calculations are performed by the computer. The principle of the calculation is very simple: the date of the start of the last menstrual bleeding and the traditional 280 calendar days are summed up.

The date obtained is approximate and corresponds to ideal medical indications. The actual timing may vary slightly depending on the individual characteristics of the woman, her state of health and the general course of pregnancy.

Pregnancy calendar, how to calculate the due date using menstruation

Find the date of your last period in the blue line of the calendar. The date that is under it (red or yellow) will be the date of birth.

Calculate due date based on date of conception

Not every woman knows exactly the day when conception occurred, so doctors cannot reliably determine the so-called “embryonic” gestational age. However, if the time of fertilization is known, then the results of calculating the time of birth will be much more accurate, because each child needs the same period for full intrauterine development. In such cases, you need to add 280 days again, this time to the date of conception.

When calculating the date of birth based on the day of fertilization, minor errors are allowed, because pregnancy could have occurred on a different day than the corresponding sexual intercourse. Research shows that conditions in the vagina are quite favorable for sperm, so they can stay here for several days before merging with the egg. The error ranges from one to three days, but no more. Thus, the date of conception determined by this method is also approximate.

Calculate due date based on ovulation

You can determine the date of birth of a baby by calculating the day of ovulation. This method is not suitable for everyone, because only a small number of women carefully monitor their menstrual cycle and, even more so, keep an ovulation calendar. If at least the approximate date of ovulation is known (with a constant cycle of 28 days, it falls in the middle), you can get a more or less accurate date of birth. To do this, you need to add 280 days to the ovulation date.

Of course, the most accurate results can be obtained if you have the maximum amount of initial data. The best option seems to be a combination of all the presented methods for calculating the date of birth. But in any case, waiting a few days is not a big problem, because the main thing is the birth of a healthy child and subsequent pleasant troubles.

Video: How to determine the due date.

ALLEGED
DATE OF DELIVERY

FIRST DAY
LAST MENSTRUATION

Last day of menstruation: Estimated date of birth: Time left until birth: Zodiac:

The gestational circle is a convenient and simple tool for determining the gestational age, expected date of birth, as well as some other information about pregnancy. Our gestational disc allows you to determine not only the gestational age, due date, but also the height and weight of the fetus, and even the zodiac sign of the future child.

Our gestational circle is very easy to use.

If you don't know your pregnancy date, scroll through the inner circle so that the green arrow points to the first day of your last period.

green arrow

Wherein “today” arrow will indicate today's date and week of pregnancy, as well as the height and weight of the fetus. Then PDR arrow will indicate the expected date of birth.

"today" arrow

If you already know your due date, then scroll the inner circle so that “today” arrow indicated the week of your pregnancy. Then it will indicate the height and weight of the fetus, and PDR arrow will indicate the expected date of birth. In this case, the green arrow will point to the first day of the last menstruation.

PDR arrow

What does "gestational" mean?

Many people hear this word for the first time in a antenatal clinic. The Latin gestatio literally translates as “gestation.” Therefore, “gestational” means “relating to pregnancy.”

Gestational age is calculated from the moment of conception. It is extremely difficult to determine exactly when this happened. It may take up to several days after sexual intercourse for a fertilized egg to implant. At the initial stage of embryo development, even a few hours play an important role. Therefore, the inaccuracy in determining the “starting point” leads to a relative arbitrariness of the calculation.

Gestational disc to determine due date

There are different calculators, the main purpose of which is to determine the date of birth of the baby. Gestational circle- an indispensable tool for preparing for childbirth and better monitoring the pregnancy process. With its help, every woman can determine the “X date” at home. This is necessary, since premature and late births pose the same danger. Therefore, it is important to calculate the expected day of birth and carefully monitor the body’s signals as it approaches.

Statistics say that about 2% of babies are born exactly on the calculated day. The date that the calculator shows is best considered conditional. Most likely, the baby will be born a few days earlier or later. Normal birth is considered between 38 and 40 weeks. But each organism has its own unique characteristics. Some women reach 42 weeks, in which case maximum attention from doctors is required.

Gestational circle is one of the most informative calculators. In addition to the approximate date of birth, it can be used to determine the height and weight of the embryo as it develops. In addition, many parents are interested in under what zodiac sign and in what year of the animal according to the eastern calendar the child will be born. For some couples, this helps them choose a name.

How does the gestational circle work?

Using this visual calculator, it is easy to determine the due date and monitor the height and weight of the fetus during pregnancy. The external drive is divided into 12 months. Each day corresponds to one division on the scale. For convenience, long marks are indicated every 5 days.

The numbers 1-40 on the moving part of the disc correspond to the weeks of pregnancy. Also, using a background with different saturation, trimesters are highlighted: the first - from to , the second - from to , the third - from to . Closer to the center is the weight scale, and at the last level is the fetal growth scale.

There are 3 arrows on the circle: green tonka (the first day of the last menstruation), EDP (estimated date of birth) and a static “today”. The center of the circle displays basic information: the beginning of the last menstruation, the expected date of birth and the child's zodiac sign. In the area under the disk, the number of weeks and days before giving birth, as well as zodiac characteristics, are instantly calculated.

How to use a gestational disc to determine your gestational age

The gestational circle is used by many obstetricians and gynecologists in different countries, including Russia. The simplicity of the method allows it to be used by absolutely every woman.

When planning a pregnancy, it is especially important to keep a menstrual calendar. This will help determine the expected date of birth as accurately as possible. To calculate the gestational age by gestational circle, simply move the thin green arrow to the date of the start of your last menstrual period. The PDP arrow will indicate the date of birth, provided that the pregnancy ends at 40 weeks. Using the “today” arrow, it is easy to track the average growth and weight of the fetus each week.

For example, the last menstruation was from December 12 to 16. For calculations based on the gestational circle, only the first date is important - December 12. Set the thin green arrow to this number. When twisting the arrow, pay attention to the center of the circle. This is much more convenient than peering at the divisions. The “today” arrow indicates that the woman is at the beginning of the 8th week of pregnancy, the fetus has grown to 18 mm and weighs 1 g. You need to prepare for childbirth within 1-2 weeks of September 18.

What should a woman do who does not know the date of her last menstrual period?

In this case, the gestational circle will be ineffective for independently determining the date of birth of the child. Doctors usually prescribe a blood test for hCG. Human chorionic gonadotropin is a hormone that is released in a woman’s body after implantation of the embryo in the uterus at 4 obstetric weeks. It is from this moment that you can get the most reliable results.

When using the strip test at home, the second strip may be translucent. This indicates either that the test is unsuitable or that there is a small amount of the hCG hormone in the body. To get reliable results, you need to try again after a week if menstruation does not start. A faint second stripe may appear in women taking hormonal medications, regardless of pregnancy.

A home test only shows the presence of pregnancy. Based on the results of a biochemical blood test, its duration is determined. Don't put off checking. The hCG test is most reliable in the first 12 weeks. The hormone level gradually decreases, and at later stages it is difficult to determine the time of conception.

Once the week of pregnancy is known, the gestational circle can be used to calculate the due date and determine the size of the fetus. To do this, just set the “today” arrow to the mark corresponding to the current date.

For example, it's week 9. At this stage of development, the embryo has reached 23 mm and weighs 2 g. The expected date of birth is September 9. The green arrow indicates the approximate date of the start of the last menstruation.

Errors

Bearing a fetus is a complex process that occurs differently for every woman. Moreover, the course of the first pregnancy does not mean that subsequent ones will follow the same scenario.

The pregnancy calculator allows for a certain amount of error. In addition, errors cannot be ruled out when setting up the source data. The accuracy of the calculation depends on the individual characteristics of the organism. The pregnancy wheel shows the most accurate result for a standard menstrual cycle of 28 days. If the duration is longer, for example, 35 days, then ovulation will occur on average on the 21st day. This leads to an increase in the difference between obstetric and embryonic periods.

In addition, the error may be caused by inaccuracy in determining the embryonic period. The sperm can survive in the female body for up to 3 days. Fertilization can occur at any time. Taking into account all factors, including the individual characteristics of the expectant mother’s body, the error in calculating the expected date of birth often reaches 2 weeks. Ultrasound gives more accurate results, although the method of calculation based on the beginning of the last menstruation is recognized throughout the world as one of the best.

Why in the first two weeks the height and weight on the disk correspond to zero

You can notice that in the first two weeks the indicators are zero. However, this period is part of the entire pregnancy cycle. The fetus develops amazingly quickly in the womb. Therefore, in determining the date of birth, every day is important. At the same time, there are different periods - obstetric and embryonic, which are important not to be confused.

Some people mistakenly believe that the first week is counted from the moment of conception. In fact, pregnancy begins on the last day of the menstrual cycle. Directly during this period, the birth of a new life might not have occurred. The moment of conception depends on ovulation and varies within a couple of weeks.

With a standard menstrual cycle lasting 28 days, the ovulation process occurs on the 14th day. In this case, the embryonic period will lag behind the obstetric period by about 2 weeks. In practice, this means that at the end of the first month of pregnancy, the actual age of the embryo is only 2 weeks.

Why sometimes calculations by different methods do not match

Many women are surprised to find that their due dates according to different calculations do not coincide. Which one should you believe?

In official medicine, it is believed that during the first trimester, embryos develop equally. On ultrasound, the gestational age is determined using a table that corresponds to the size of the fetus for a certain period of development. For example, a calculation based on the last menstruation shows a result of 12 weeks, but the diagnostician calls it 11 weeks. The deadline set during the first ultrasound is considered more reliable. In the example given, the difference is due to early ovulation, but it can also be late. For the doctor, the result of the ultrasound examination is a priority.

During the second and third trimesters, each fetus develops at its own pace. Therefore, data from average tables may not fully correspond to reality. Deviations within one week are considered normal. In the ultrasound protocol, the specialist indicates the period of fetal development.

The gestational circle gives an idea of how the unborn baby is developing every day. At the beginning of the first trimester, the embryo gains only a couple of grams every week, but the difference, for example, between and 21 weeks is on average 71 g. Every woman is interested in learning how the fetus changes. With the gestational circle, observing becomes simple and even more fun.

The most important weeks of pregnancy

In order for the fetus to develop correctly and the child to be born healthy, the fact of pregnancy must be established as early as possible. It is not at all necessary that the expectant mother will intuitively sense conception, or that obvious signs will appear in the first weeks in the form of a heightened sense of smell, morning sickness, etc. There are often cases when a woman learns about pregnancy only by an enlarged belly.

The following factors pose a particular danger to pregnant women:

Unhealthy habits.
Stress.
Unbalanced diet, deficiency of nutrients (mainly iron and folic acid).
Great physical activity.
Overheating or hypothermia.
Taking medications that are incompatible with pregnancy.
Infectious and inflammatory diseases.

It is necessary to prepare the body in advance for pregnancy in order to minimize risks for the fetus and the expectant mother. But even if everything goes according to plan, there are times when you need to be extra careful. If at any stage of pregnancy a woman feels severe discomfort, burning or even unreasonable anxiety, she should visit a doctor.

When to take extra care

Critical periods coincide with the phases of active enlargement of the embryo and placenta. The most dangerous weeks are the following:

I trimester - 2-3, 4-7, 8-12.
II trimester - 18-22.
III trimester - 28-32.

The tricky thing about the first weeks is that a woman may not be aware of pregnancy. As a result, the required conditions are not met. From 4 weeks the main organs are formed. During this period, it is especially important to follow the doctor’s instructions in order to prevent pathologies. At the last critical stage of the first trimester, the placenta is formed - a natural shield that will grow with the fetus.

The period from week 22 is considered the most important. At this time, the unborn baby is most active. The greatest risks to the life of the fetus and the health of the woman are sexually transmitted infections. One of the main conditions is to use barrier protection during sexual intercourse.

By the beginning of the third trimester, the fetus is most similar to a baby, but it is not yet able to survive separately from the mother’s body. The causes of premature birth may lie in placental abruption, infections and isthmic-cervical insufficiency. To prevent this, you need to follow absolutely all the doctor’s instructions, take care of your own health and eliminate stress.

There are no critical periods in the gestational cycle. This is because they don't have to be difficult at all. The more you focus on the dangers, the greater the destructive effects of stress. You can use the pregnancy wheel throughout the entire pregnancy period. The diagram is convenient for tracking the transition to a new trimester, the stages passed and the approaching date of birth.

Description

The universal pregnancy calculator is a convenient and practical tool for calculating a number of parameters that are important and interesting for the expectant mother. The calculator is a circle similar to a watch dial, the inside of which can be rotated to set one or another hand to the desired position. For example, by setting a thin green arrow so that it points to the first day of the last menstruation, you will use the “PDR” arrow to determine the date of future birth, and by using the “today” arrow you will find out what week of pregnancy you are now, and what the height and weight of the fetus is. present day. The Pregnancy Wheel can be used in other ways. For example, if the birth has already taken place, then you can set the “Estimated date of birth” arrow so that it points to the day of birth. Then a thin green arrow will show you the date on which you had your last menstrual period before becoming pregnant. Among other things, the calculator determines the zodiac sign of the unborn child, and even his zodiac animal according to the eastern calendar.