Calculate your due date based on your last period. Obstetric method, other methods. Due Date Calculator Determine due date from last period

The birth of a child is a long-awaited event for every woman. Barely pregnant, the expectant mother is trying to figure out when her baby will see the light. There are many methods for determining the date of birth. You can calculate this important day in the life of every married couple using the Negele formula. In addition, you can determine when the baby is born, based on data on ovulation or conception. The calculation of the expected term of delivery in gynecology is carried out according to the indications of ultrasound, the first movement of the fetus or the weight gain of the future woman in labor.

Methods for determining the PDR (preliminary date of birth)

Often, the expected date of birth (hereinafter - PDR), set by the woman herself, differs from the day the baby is born, which is calculated by the doctor. This situation is explained by the fact that there is an obstetric and embryonic (in other words, true) gestational age, calculated on the basis of information about conception. The embryonic period is usually shorter than the obstetric period by about 14 days. In the latter case, we are talking about the date, the determination of which the doctor carries out, guided by the first day of the menstruation preceding the conception of the child.

In obstetric practice, this concept is used. Establishing the size of the fetus, the time of the necessary examinations, the day of the start of maternity leave, as well as delivery, is carried out solely on the basis of the obstetric gestational age.
The effectiveness of a screening study, a diagnostic method that allows timely detection of congenital abnormalities in a child in the womb, depends on how accurately the gynecologist determines when the patient will begin labor activity.

When a future woman in labor first visits the gynecological office, the doctor calculates the expected date of delivery. This procedure is based on the application of several techniques.

By date of last menstrual period

They will find out after how much time the long-awaited baby will be born, according to the date of the menstruation preceding the conception (regulatives). To do this, from it in reverse order, you should count the 3-month period and add 7 days. The resulting number is the preliminary due date. Most doctors, when using this technique, resort to the help of special obstetric pregnancy calendars. It is difficult to accurately calculate the date of birth by menstruation in situations where the future woman in labor has an unstable menstrual cycle or when it is regular, but too long.

For example, if a patient has a 35-day interval between the previous and subsequent bleeding, and not 26-28 days, as in most cases, then most likely she will not be able to conceive a baby on the 14th day of the menstrual cycle, as happens in standard situations, but only on the 21st day. With this in mind, when calculating the estimated due date using this method, it will be revealed that the woman in this situation will have time to give birth 7 days earlier than the true estimated date of birth of the baby.

Ovulation date or conception date

During pregnancy, it is quite easy to predict the date of birth, if you have reliable information about the moment at which the egg was fertilized. To determine how much time is left before delivery, you need to add 266 days to this number - that is exactly how much time is needed on average for the full development of the fetus. Despite its apparent simplicity, this method of determining the due date has several subtleties.

If a pregnant woman knows exactly the date of ovulation or sexual intercourse during which she became pregnant, it is still impossible to speak with complete certainty about the day of conception. The average lifespan of spermatozoa is up to 7 days, the ability of a mature egg to fertilize remains for 2 days after ovulation.

As a result, even taking into account the exact date of sexual intercourse or the release of a mature egg from the ovarian follicle, it is impossible to reliably calculate at what specific moment conception occurred, since this could happen later. In this regard, doctors consider this algorithm for determining future births approximate and use it to calculate the approximate moment of delivery.

According to ultrasound

This technique allows you to most correctly set the date of birth. For the first time, ultrasound is performed at 4-5 weeks of gestation. In the uterine cavity, using ultrasound, a fetal egg is determined, which is a small black circle, in which subsequently, at 6-7 weeks, an embryo appears. It looks like a small strip in which you can detect a heartbeat.

The most accurate is the PDR, determined on the basis of the coccyx-parietal size, which is the size of the embryo, that is, the maximum distance from the highest point of the crown of the fetus to the lower point of the coccyx. After the 12th week of pregnancy, in the process of ultrasound, the calculation of the due date is carried out taking into account the parameters of the baby's head and tummy, as well as the length of his arms and legs.

Up to 9-10 weeks, the fetus develops proportionally, so its size in women with the same gestational age is usually the same. In the future, this indicator begins to vary in future women in labor.

The difference in values ​​in this case depends on many factors:

• the nationality of the woman;
• her weight;
• body weight of both parents at birth.

In other words, the less time remains before childbirth, the more noticeable are the differences in the intrauterine development of a fetus that does not have defects. In some cases, fluctuations in the parameters of children of the same age in the mother's womb can range from 14 days or more. This discrepancy makes it impossible to reliably establish the moment of birth according to the results of ultrasound.

By the first movement of the fetus

You can calculate the preliminary date of delivery using information about the first movement of the fetus. For the first time, a woman who is preparing to become a mother for the first time begins to feel signs of a child in her womb at about the 20th week of pregnancy, and a future more experienced woman in labor at the 18th week.

Doctors recommend that patients remember this important point, information about which must be entered in the exchange card. To establish the PDR, 20 and 22 weeks are added to the indicated number: for patients who are pregnant for the first time and for women who have already given birth, respectively.

Despite its simplicity, this method is rarely used in modern gynecology. The unreliability of its results is explained by the fact that future women in labor at different intervals for the first time feel the movements of the fetus.

Many factors influence this:

• sensitivity of the expectant mother;
• features of her physique;
• Lifestyle;
• the presence or absence of motherhood experience.

Some future women in labor feel the first tremors in the abdomen as early as 15-16 weeks, others only after the 20-week period. According to statistics, this happens much earlier in a slender woman than in an overweight expectant mother. Those pregnant women who lead a very mobile lifestyle and devote a lot of time to work often feel the movements of the fetus for the first time later than those who are much less busy and live a measured life. Primiparous women often take the first movements for indigestion, and more experienced expectant mothers immediately determine if the baby in the womb first made itself felt.

By weight gain

Along with the above methods, you can also calculate the approximate date of delivery, focusing on weight gain in the process of bearing a baby. On average, this figure from the moment of conception and the birth of one fetus increases by 9-14 kg, two or more - by 21 kg.

The body weight of the future woman in labor begins to grow, as a rule, in the second trimester. The gain in this case is about 1 kg. With the flow of pregnancy in the third trimester, the woman's weight increases to 500 g every 7 days. Taking into account a specially developed table of weight gain during pregnancy, it is possible to compare the readings of the values ​​during the control weighing.

Doctors use tabular indicators starting from the 7th month of pregnancy, after which the most active weight gain occurs. This table is based on body mass index (BMI) and assumes that the normal weight of the expectant mother in 7 days should increase by 20 g for every 10 mm of fetal growth. Each type and group of a female figure corresponds to a certain BMI value:

• thin (group 1) - ≤ 19.8;
• medium build (group 2) - 19.8-26;
• obese (group 3) - ≥ 26.

Table of indicators of the increase in the body weight of the expectant mother:

Negele formulas

The method for determining the preliminary date of the birth of a baby, based on information about the latest regulations, was invented by the German obstetrician Karl Franz Negele. Most of the studies of this outstanding scientist in modern obstetrics are fundamental. Many obstetricians and gynecologists today use the rule derived by a talented colleague from Germany.

This technique is very convenient for independent use. In order to use it to calculate the upcoming date of the birth of the long-awaited baby, it is enough to know the 1st day of the menstruation preceding the conception and have a calendar at hand. However, its use has one caveat: a woman must have a regular menstrual cycle, averaging 28 days. Negele formula: PDR = start date of the last regulations - 3 months + 7 days.

How to determine the expected date of birth in IVF (in vitro fertilization)?

This technique, which involves the artificial fertilization of an egg, was created specifically for couples who, for whatever reason, cannot conceive a child naturally. Initially, the embryos develop over a 3-5 day period in a laboratory environment and then implant into the uterine cavity.

The embryonic gestational age, which occurred with the help of artificial insemination, is counted from the moment of ovarian puncture. To establish the obstetric period from the date of this procedure, 14 days are counted forward.

If before the introduction of the embryo into the uterine cavity, it was deep frozen with liquid nitrogen (cryopreservation), then to calculate the embryonic gestational age, 5 days should be added to the date of the final stage of IVF - this is how much time the embryo needs to develop before freezing. To establish the obstetric period in this situation, 14 days are counted from the true forward and only after that the date of delivery is determined.

What deviations from the deadline are considered normal?

All of the above methods of establishing the date of delivery are conditional. None of them will be able to accurately answer the question on what specific day the long-awaited baby will be born. According to statistics, only in 17% of cases this event occurs at a predetermined moment.

In other situations, a woman first begins to feel contractions later or earlier than the appointed date. For this reason, no doctor, no matter how great his experience and high qualifications, will be able to predict on which particular day the patient will begin labor.

It is considered normal if the baby is born in the 38-42-week interval from the beginning of pregnancy. In other cases, we are talking about prematurity or overmaturity of the fetus. However, there are a number of exceptions to this:

• genetic predisposition to deviate from the standard duration of bearing a baby;
• being in the womb of more than one fetus (twins and twins are often born before the appointed date).

Many women, especially those who are expecting their first child, do not understand why the doctor gave this or that date of birth, although according to their calculations, it turned out that the baby should be born earlier. You should not worry, the doctor was not mistaken, you too. How can this be? The fact is that there is a true gestational age and obstetric, they differ from each other by two weeks.

With any pregnancy, the estimated due date is always calculated. There are several methods for calculating the approximate date of birth.

• Embryonic. This is the real term, i.e. That's how long a normal pregnancy lasts. From the date of conception to delivery, it usually takes 266 days or, in terms of weeks, 38 weeks.
• Obstetric. This period is usually recorded in the patient's card. The doctor cannot know the date of conception of the child. Medicine is an exact science, it cannot be based on the assumptions of a woman. Therefore, obstetricians-gynecologists use their own method. The countdown is not from conception, but from 1 day of menstruation before pregnancy. This period differs from the true one, its duration is 280 days (forty weeks).

Calculation by day of menstruation

The most common way that helps to calculate the expected date of birth quickly is by the last menstruation.

• Think back to the day you started your last period before pregnancy. Mark this day on your calendar.
• Now subtract three months (we step backwards on the calendar).
• Add seven days to the received date.

Let's say your last critical days began on July 15th. We count down three months - it turns out April 15th. Add 7 days to this date. The date of the birth of the baby is April 22.

You can quite accurately calculate the term of childbirth by the date of menstruation, if a woman has a regular cycle and it lasts from 26 to 28 days. If it is slightly longer, for example 35 days, the result that was obtained will be incorrect. In this case, conception should occur on the 21st day of the cycle, and not on the 14th, as in many women, i.e. labor can start up to 7 days later. If the cycle is short, less than 24 days, then the date of delivery also moves by about 7 days, they should begin earlier.

Calculation using a calendar

If you find it difficult to make these calculations or you doubt that everything is correct, use the birth calendar to calculate this day from the date of the last period. The top line is the time of the onset of menstruation, below it is the expected date of birth.

Or you can use the online calculators that are available on many sites. It is enough to enter the date of the beginning of the last menstruation in a special window, after which the system will give the desired answer. Now online pregnancy calendars are very popular, they will not only help you calculate the date of birth, but also tell you what is happening in a woman’s body. So the expectant mother will be able to monitor the development of her baby, find out what changes have already occurred. If you wish, you can even order your own individual calendar, where it will be scheduled in time as the child grows.

Calculation by date of conception

How to correctly calculate the date of birth if menstruation is irregular? There is another way that will help calculate the date of birth by the date of conception. You need to remember on which day the conception of the child occurred. Then add 266 days to this figure. That is how many days a woman usually bears a baby. You can also calculate the date of birth by weeks of pregnancy, because. sometimes it's hard to count the days. On average, after conception, pregnancy lasts 38 weeks. Using the calendar, it is easy to calculate the due date according to the known date of conception.

Are these methods reliable?

If you calculate the date of birth by the last menstrual period, is the baby exactly born on that day? No, according to statistics, only 5% of children are born on the “settlement day”, this is an approximate date, babies are born within a week (plus or minus) of this day (85%), and about 10% of children may be one more late week.

Also, if you calculate the correct date of birth according to the day of conception, there may be errors. Not everyone can name the date of conception of a child, because. this date sometimes does not coincide with the day when there was intimacy. The sperm can remain in the body and fertilize a woman for 4-5 days after intimacy, i.e. a woman could have sex one day and conceive a child later. But, even if the calculation was correct, the birth may be premature due to various diseases, due to severe stress, etc.

Additional ways to determine pregnancy

• A trip to the gynecologist. As soon as the expectant mother comes to the doctor, the gynecologist examines her and finds out what her gestational age is. Accurate results can be called for a period of 5 to 12 weeks by measuring the size of the uterus. The blood test of a pregnant woman for hCG is also important. This hormone is produced only in the body of a woman who is expecting a child, at different times its concentration in the blood is different. The doctor has tables that indicate how much hCG should be at one time or another.
• ultrasound. The physician must measure the size of the fetal egg, as well as the embryo. Up to 9-10 weeks, the indicators for all women at a certain period are the same. From them you can find out the duration of pregnancy. Later, this method will not work, because. after 10 weeks, the size of the fetus in different women can vary significantly, depending on the weight of the mother, on nationality and on other factors that affect the weight of her baby.
• By the first move. It is believed that a mother expecting her first child feels 1 movement at twenty weeks, and the rest of the pregnant women at eighteen weeks. Based on this knowledge, you can calculate the date of birth: for the first time a pregnant woman, add twenty weeks to this date, and for a woman who has already given birth - 22 weeks. But some mothers feel the movement of the baby as early as 15-16 weeks, and others after 20 weeks, so these numbers will not be accurate.
• There are many ways to calculate due date. You should not hope that the child will be born on this very day, but it is important for a woman to know at least approximate dates in order to complete all her affairs, pack her things and prepare for the birth of the baby. This information is also necessary for the doctor who leads the pregnancy to make sure that it is proceeding normally.

As we can see, it is not difficult to make such calculations; you can calculate the desired number in just a few minutes.

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

The emotional coloring of the news about the expectation of the 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 quite natural desire is due to both practical goals and simple human curiosity:

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

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

Toward the end of the third trimester, women usually begin to calculate the estimated date by all possible methods, double-checking it again and again, because they feel heaviness and fatigue, and they can not wait to meet their baby as soon as possible.

How to correctly calculate the due date? Table

Almost everyone 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?
• months to take calendar or conditional for 30 days, how many days exactly in them?

When an expectant mother is faced with pregnancy for the first time, a period of nine months seems to be something very uncertain, and in order to calculate the date of birth as close to reality as possible, I want specifics.

The generally accepted method for determining the expected date of delivery (hereinafter - EDD) in order to monitor the development of the fetus and pregnancy in general is the countdown from the date of the start of the menstrual cycle.

EDD \u003d date of menstruation + 280 days (or 40 weeks)

This method sets the conditional boundaries of pregnancy, called obstetric period, which becomes a guideline for doctors and expectant mothers to monitor the development of the baby. When a woman is asked the question of how long she is, the pregnant woman will name exactly the obstetric week of pregnancy.

In fact, the true pregnancy came later than the date of the last menstruation by about two weeks, respectively, 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 still only in the plans of potential parents? To find an answer, let's briefly consider what happens in a woman's "pregnant" cycle and at what time:

1. no matter when intimacy took place, fertilization or conception will occur on the day of ovulation, and taking into account the vitality of spermatozoa, the difference between these moments can reach up to 5 days
2. ovulation occurs on average 14-15 days before the end of the cycle (next menstruation), but can occur earlier (16 days) and later (12-13 days)
3. conception does not guarantee pregnancy, for this a fertilized egg must attach to the uterus, or be implanted, which takes 6-8 days on average, but can also vary over time

IMPORTANT: 80% of conception cases end in unsuccessful implantation, that is, pregnancy does not occur, but the woman does not even know about it, since menstruation occurs 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 time
• day of ovulation
• 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
• the nature of the pregnancy
• mother's age and health
• 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 at what time it takes place 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)
• timing of implantation fall within the normal range

If you fit into the specified parameters, you can safely look in the table below for the date of the proposed meeting with the baby. No one guarantees the exact probability, but this is the most approximate time.

• 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
• under it, the estimated date of birth and the month will be indicated (indicated in crimson)

Examples shown in the table:

1. in a woman with the first day of the last menstruation on March 28, the birth is planned for January 2
2. if the beginning of menstruation was 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 run of 1-2 weeks is considered a normal option. In other words, from the point of view of medical science, the ideal pregnancy is 40 obstetric weeks, but more often falls in the range of 38-42 weeks.

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

How to calculate due date by ovulation?

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

For example, ovulation became known using:

• Ultrasound, which a 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
• own explicit sensations due to long-term observations of your body

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

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

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

Recent studies by staff at the US National Institutes of Health concluded that pregnancy is more likely to be 268 days from the day of ovulation (rather than the accepted 266), that is, 38 weeks and 2 days. The duration of the gestational period also depends on how long it takes for the implantation of the fetus in the uterus. This point in the study was recorded on the first day of hCG growth.

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

How to calculate due date from conception date?

Conception or fertilization occurs when the sperm and 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 EDD based on the date of conception is similar to the method based on the date of ovulation described above.

IMPORTANT: It is necessary to 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 lifespan of the sperm of a particular man.

How to calculate the due date exactly by menstruation?

The estimated date of birth, which the gynecologist will announce to the woman, as mentioned above, is based on data on the last menstruation. In this case, the day the cycle began 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 an easier way (Negele's formula):

PDR \u003d date of menstruation - 3 months + 7 days + 1 year

Example #1:

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

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

Example #2:

• start date of the last menstruation - December 15, 2015
• subtract three months, we get September 15, 2015
• sum of days of subtracted months: november (30) + october (31) + september (30) = 91
• therefore, we add 6 days, we get September 21
• add year, DA - September 21, 2016

Example #3:

• date of menstruation - May 2, 2015
• minus three months - February 2
• sum of days in April, March and February (non-leap year) - 89
• so add 4 days to the result
• in the end, DA - February 6, 2016

How to calculate the date of birth with an irregular cycle?

The calculation of the due date 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 a situation:

• the date of the last menstruation of a woman is September 12, the EDD 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, the doctor will ask about the duration of her menstrual cycle
• meanwhile, the cycle of the expectant mother is 40 days, which means that the date of birth, for objective reasons, is shifted by at least 12 days
• ovulation, most likely, did not occur 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 has not yet “walked over”, the duration of her true pregnancy has not yet reached 266 days, there are no reasons for unrest

Thus, it is quite natural that childbirth has not yet occurred, and the explanation for this is logical: the woman had a 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 the date of ovulation 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 EDD calculated from the menstruation
• if the cycle is less than 28 days, subtract the difference from the EDD calculated from the menstruation

In the example above:

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

How to correctly calculate the date of birth according to the first ultrasound?

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

With the help of ultrasound, the doctor will evaluate the coccyx-parietal size of the fetus, by which it is possible to determine the gestational age.

For example, if the CTE of the fetus is 44 mm, the gestational age on ultrasound is 11 weeks and 2 days (or 79 days).

The table indicates the obstetric period. Accordingly, 201 days (=280-79) or 28 weeks and 5 days remained until delivery.

In the 2nd and 3rd trimesters, the accuracy of matching the parameters of the fetus 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 due date after IVF?

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

How to calculate the date of birth by the first movement of the fetus?

Fetal movement, although quite specific and real, is a subjective factor in 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 pushes and movements. Primiparous women notice this later than more experienced mothers, they are often confused with the processes taking place in the intestines, they think up something that they still cannot feel.

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

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

The different terms are explained by the fact that the first feel movements only at 18-20 weeks, and the second - from 16 weeks.

But this method can only roughly estimate the period of childbirth. At what point a woman will fix the first movement, it also depends on the structural features of the uterus, on the method of attaching the fetus to the wall of the uterus, on the sensitivity of the woman 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 lighter than the previous one. This is not always the case and depends on the individual. But often, nevertheless, the second birth occurs earlier, at 38 weeks, while the first - on average at 39-40 weeks. Otherwise, the calculation of the PDR is similar to the principle of determining the date of the first birth.

• It is known that the main guideline for calculating the EDD is the last menstruation, but there are frequent cases when a woman becomes pregnant again with a cycle not yet renewed after the first birth
• How to be in this case? A woman does not know the date of the last menstruation simply because they have not yet been after the first pregnancy
• In such circumstances, the period is usually set according to the results of 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

1. If the menstrual cycle is 28-30 days, then the date of birth calculated in the antenatal clinic (by menstruation) will be the closest to the truth
2. If the cycle differs significantly in duration from the standard one or fluctuates from time to time by more than 3-4 days, inform the gynecologist about this when registering
3. In this case, keep in mind that labor can start earlier or later than the due date by the number of days your cycle is shorter or longer than the standard 28-day period.
4. You should not get too hung up on calculating the date of birth, the percentage of exact hits is still not high
5. Prepare mentally in advance that childbirth may occur earlier or later than the due date
6. If the first birth occurred exactly on the due date, this does not mean that the same will be the case with the second
7. Remember that PDR is primarily needed for medical purposes: establishing significant abnormalities in the development of the fetus depending on the gestational age, 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 date of birth?

This day requires special preparation. There are so many things to buy, cook, study a huge amount of literature, think through all possible scenarios. And it seems to us, women, that it would be a shame not to take into account something.

The whole pregnancy is not only a spiritual mood, but also quite material chores that should be carefully planned.

In a simple formula due date calculation the main component is the gestational age. Conception occurs most often on the days of ovulation, but not every woman knows when these very days come.

Everything is simple - exactly in the middle of the menstrual cycle, i.e. 12-16 days after the first day of the last menstruation.

For example, your last menstruation began on April 1, which means that the egg will go on its difficult path on April 12-16.

This due date calculation is suitable for women with an average menstrual cycle of 24-28 days. With deviations by day in one direction or another, the ovulation period also changes.

Let's assume that conception occurred in the middle of the last menstrual cycle. From this period of time, the long 40 weeks of your pregnancy begin.

Trying to calculate the due date by week

Some women mistakenly add 9 months and get a "supposed" sacred date. This is not true, because pregnancy lasts a little longer - approximately 280 days or 40 weeks.

True, the doctor quickly eliminates this error and helps the patient decide with the help of a special calendar that any gynecologist has.

This calendar has the easiest counting system - from the first day of the last menstruation you need to subtract 3 months (April 1 minus 3 months = January 1), then you need to add 7 days to the resulting date (1 + 7 = 8), the result is the estimated date childbirth, which your gynecologist will enter on the card.

The second calculation method is to add 280 days to the first day of the menstrual cycle.

But you can’t rely only on these calculation systems, because for some, a full-term pregnancy can last 38 weeks, while for others - 42, all this is within the normal range.

Multiple pregnancy, as a rule, ends earlier than the date calculated by the doctor.

How to correctly calculate the term of childbirth by movements. Folk omens

To determine the term of childbirth, you can use a folk omen, which for many centuries, even before the development of medicine, helped expectant mothers.

Exactly in the middle of pregnancy, primiparous women for the first time feel the movements of their baby - this significant event occurs, as a rule, at the 20th week.

Multiparous mothers identify tremors as early as 18 weeks. the walls of the uterus after childbirth become thinner, and therefore more sensitive, therefore, the second / third / fourth time intrauterine movements are perceived better.

By the time of the onset of intrauterine movements, you need to add 20 and 22 weeks for the first and subsequent pregnancies, respectively.

But this method is not very accurate either, because girls with different builds feel tremors at different weeks, a thin woman feels movements inside herself already at 15-16 weeks, and a denser woman at 21-22 weeks.

It is worth adding that not all expectant mothers can immediately correctly evaluate incomprehensible movements inside themselves - some confuse this action with an intestinal disorder, sorry, or a movement of the abdominal muscles (a weak cramp).

You can also determine the approaching birth already in the last trimester - by lowering the tummy. This process makes pregnant women feel a little better and takes place 2-4 weeks before delivery.

Calculate due date by ultrasound

Another method for assessing the term of childbirth is computer diagnostics, or more simply, ultrasound. In the early stages (up to 12 weeks), ultrasound can accurately determine the day of conception, based on the size of the head and torso of the embryo.

Up to a certain point (approximately 3-4 months of pregnancy), all babies develop in the same way, after which the genetic predisposition, the mother's diet and lifestyle affect.

Ultrasound examination in the second and third trimesters will have an error of up to 2-3 weeks, because the children are different and the weight of newborns can vary from 3 to 5 kilograms.

Inexperienced gynecologists can use the date calculated by the computer as a basis, and after the "estimated 40 weeks", begin to take unnecessary measures in connection with the "delayed" pregnancy.

Finally, almost as accurate as an ultrasound can be considered a gynecological examination on a chair.

An experienced doctor, by the size and shape of the uterus, will be able to determine the gestational age by touch, based on which further calculations will be made, which we determined at the beginning of the article.

It should be borne in mind that you cannot rely one hundred percent on any of the listed methods, they are approximate and give a result that can vary by 2 weeks in one direction or another. It is worth focusing on your feelings and nature, which is never wrong.

Childbirth occurs 280 days after conception. The actual date of delivery may differ from the estimated date by up to 2 weeks. Methods for determining the date of birth are common: ultrasound, hCG level, tables and calendars.

Various methods for determining the gestational age and calculating the due date

According to popular belief, pregnancy lasts exactly nine months.

This is not so - the period is 40 weeks, 280 days from the moment of conception. The date of birth is clearly determined by gynecologists when examining a patient.

How doctors determine the date of birth: why is it needed

Determining the date is necessary in order to:

• the woman was mentally and physically able to prepare for the event;
• to track whether the fetus is developing correctly, whether its condition is normal.

In 90% of cases, the date of the expected birth does not coincide with the real one. This is due to the fact that it is impossible to determine the exact day when fertilization with a spermatozoon occurred. The development of each fetus individually. A woman should not worry about this - fluctuations up to two weeks from the expected day do not pose a threat.

How long does it take to calculate

Doctors determine the relatively accurate time of delivery with an ultrasound examination of the uterus during the first 3 months after conception.

The first ultrasound is usually performed before the 12th week of pregnancy. Then the specialist determines the date of birth depending on the size of the fetus.

It is possible to find out exactly the EDD up to 12 weeks. It is explained by the fact that after 3 months the fetus develops individually: the weight and size indicators of some increase, while others, on the contrary, do not hold out. It cannot be said that this increase or decrease in weight is somehow dangerous for the unborn child and mother. Small deviations do not affect the physiological processes, but may determine the choice in the direction of artificial childbirth.

The best option is to do an ultrasound within 2 weeks after the start of the delay. If the pregnancy proceeds without pathologies, it is possible to calculate the time of birth with an accuracy of 1-2 days.

How weeks of pregnancy are counted in gynecology

This technique, like ultrasound, shows reliable results only up to 12 weeks. The increase in the uterus in different women varies depending on individual indicators.

Methods for determining

Modern medicine offers three main methods by which the time of the birth of a child is calculated.

How to calculate the date of birth by the last menstruation

The obstetric technique or calculation by the time of the last menstruation is popular and allows a woman to independently calculate. There are special obstetric calendars on the Internet.

Formula: from the first day of the last critical days minus 3 months and add 7 days. Therefore, 40 weeks are added to the first day.

The method is not accurate, because the PDR often does not coincide with the obstetric one. The date of delivery may move 2-7 days with this method of calculation.

Date table by last monthly with an example of self-calculation

The following information is required for the calculation:

1. duration of menstruation.
2. Selection type.
3. Cyclicity (from 28 to 32 days).

Calculation example: March 20 (date of the first day of critical days) - 3 months + 7 days = December 27. With irregular periods, this technique is not suitable.

To simplify the calculations, special tables have been created in which the estimated time of conception is written in the top line, and the estimated date of birth is written below it. A woman will only need to remember the day of conception. This calculation method is suitable for those who have a menstrual cycle of 28 days.

Table analogues are online calculators. You just need to enter information into them and the calculation will happen automatically. Calculators are the best option for women with unstable menstruation. For calculation, they do not use a ready-made algorithm, but add up the numbers of the last menstrual cycles for the last six months and reveal the arithmetic mean.

Is it possible to calculate the date of ovulation

Fertilization is possible when the egg is released from the ovary. This phenomenon is observed on the 12-14th day of the monthly cycle. The calculation algorithm is as follows: 280 days are added to the middle of the cycle. If the sexual intercourse was the only one during the cycle, then the calculation is accurate.

Ovulation does not always occur in the middle of the cycle. Therefore, it is highly likely that fertilization was several days later. Therefore, the technique cannot be called accurate, there is an error of 2-7 days.

How to accurately calculate the date of birth by ultrasound

The maximum accuracy is up to one day, but only if the study was conducted up to 12 weeks.

What determines the accuracy of ultrasound in determining the number of births

The accuracy of an ultrasound examination depends not only on the experience of the doctor and the equipment used. Women who come for an ultrasound do not always report the correct gestational age. The specialist, focusing on the development of the child, puts the wrong due date.

On what ultrasound will they tell about the date of birth

An ultrasound examination, which was performed for the first time, indicates the date of birth, even when it is still impossible to determine the sex of the child. It is impossible to calculate the PDR for later ones.

Is it possible to determine the date of birth by analyzing hormones and the level of hCG

The "pregnancy hormone" increases significantly during the period of bearing a child.

The results of a blood test from a vein for hCG are deciphered by the doctor, based on knowledge of the woman's hormonal background and previous indicators. In most cases, the indicator increases up to 21 weeks, and then gradually decreases.

• 1 week - 5.3 - 50;
• 2 weeks - 50 - 500;
• 3 week - 101 - 4870;
• 4 week - 1110 - 31500;
• 5 week - 5660 - 82300;
• 6 week - 23100 - 151000;
• 7 week - 27300 - 23300;
• up to 11 weeks - 10900 - 291000;
• up to 16 weeks - 6140 - 103000;
• up to 21 weeks - up to 801000;
• up to 39 weeks - up to 78100.

It is possible to calculate the PDR with an error of up to a week. The definition is simple: compare the level of hCG with the norms. For example, if the hormone content is about 4000, then this indicates a 3-4 week, 700 - the second. It is important to note that:

• earlier than 10 days after ovulation, it is pointless to do calculations, since the concentration is insufficient for analysis;
• the level of hCG increases ten or more times during pregnancy;
• around 20 weeks, the hormone stabilizes and remains the same until the end of pregnancy.

What harbingers of the onset of labor should not be missed

The main symptomatology begins to be expressed a month before the event. Usually present:

uncomfortable sensations;

• false contractions;
• change in the emotional background;
• weight loss;
• prolapse of the abdomen;
• discharge of the mucous plug;
• change in the quality and regularity of the chair;
• decreased appetite.

Harbingers are natural. They show that the body is training for the upcoming birth.

It is not necessary to call a doctor if, according to all indicators, childbirth has not yet occurred or the symptoms are not pronounced.

Is it possible to determine the exact date of birth on your own by the estimated date of conception

The method is used if it is known exactly when there was sexual intercourse and it was the only one for the entire period of the menstrual cycle. 266 days are added to the PA date.

The sperm that entered the female body is capable of fertilization for up to a week. The calculation error is up to 7 days.

Is it possible to determine the date of birth with an irregular menstrual cycle

Irregular periods make calculations difficult. Fertilization of the egg could not occur on the 12-14th day of the cycle. In this case, PDR is detected during ultrasound and on examination.

What to Consider

It is impossible to accurately calculate the date of birth. This should not worry the expectant mother too much. If the child does not appear on the day appointed by the doctor, and later for several days of the week, you should not panic. This means that the child took more time to prepare for the birth.

There are dozens of ways to find information. The most reliable are the level of hCG, ultrasound and gynecological examination. Others also show relatively correct information, but the regularity of the cycle affects the indicators.