Calculate the day of birth from the day of conception. How to determine the date of birth: ways. Deviation from the deadline is the norm

Estimated date of birth(PDR) is considered the day when the gestational age is exactly 40 weeks. Although a full-term pregnancy is considered already after reaching the full 37 weeks, and in some cases a healthy full-term baby can be born at 42 weeks of pregnancy, it is still customary to focus on 40 weeks, since most births begin at this time.

Importance of Calculation estimated date the birth of a baby is beyond doubt, and the point here is not only the desire of parents to prepare for the appearance of a new family member. The medical side of the matter is also important. We list the reasons why the doctor leading the pregnancy needs to know the expected date of birth.

Growth and development of the fetus. It is important for a doctor observing the course of pregnancy to know how the developing baby corresponds in size to the gestational age (which is calculated based on the expected date of birth) in order to timely diagnose such a serious complication as intrauterine growth retardation (IUGR), which is a consequence of placental insufficiency (pathology , in which the placenta inadequately performs the functions of providing the fetus with everything necessary for growth and development). Timely adequate diagnosis and, consequently, the treatment of this complication is of great importance for the further full development of the baby.

Prevention of pregnancy complications. In the process of observation, the obstetrician remembers that certain complications may develop at various stages of pregnancy, and therefore, the terms are determined in which it is necessary to carry out diagnostic measures to identify complications, their prevention and treatment (for example, prenatal screening - diagnosis congenital malformations of the fetus - should be carried out at clearly defined terms of pregnancy, and if these terms are not observed, its diagnostic value is sharply reduced). In diseases such as diabetes mellitus and hypertension, for example, if the course of the disease worsens or treatment does not give a positive effect, it may be necessary to deliver before the spontaneous onset of labor. Then the doctor needs to know in order to ensure the maximum possible degree of fetal maturity in this clinical situation.

When to go to the hospital

If there are indications for early hospitalization before delivery, it is important to correctly determine the timing in which the pregnant woman should go to the hospital. After all, with too late hospitalization (for example, on the eve of a planned cesarean section), there is a risk of not having time to carry out the necessary amount of examination and preparation for delivery, and too early hospitalization is not advisable, since a long stay of a future mother in a hospital can lead to an increased level of anxiety, stress on the eve childbirth. Terms of antenatal hospitalization for various complications during pregnancy may vary. For example, with diabetes, it is necessary to hospitalize a pregnant woman no later than 36 weeks. With the transverse position of the fetus and placenta previa, the expectant mother should be in a hospital no later than 37 weeks (since during this period the processes of preparing the body for childbirth begin, which is very dangerous due to prenatal rupture of amniotic fluid in the case of a transverse position of the fetus and the development of bleeding during presentation placenta). Women with breech presentation and anatomically narrow pelvis are sent for antenatal hospitalization at 38–39 weeks of gestation in order to have time to conduct a complete examination, choose the method of delivery, and prevent pregnancy from being overdue.

How to calculate due date

For determining estimated date of birth several methods are used.

obstetric term(according to the date of the last menstruation). It is generally accepted to consider the date of the reference of the menstrual cycle as the date of the first day of the last menstruation - that is, the full menstrual cycle is calculated as the interval from the first day of menstruation to the first day of the next menstruation.

For calculation estimated date of birth By the date of menstruation, there are two ways:

280 days are added to the date of the first day of the last menstruation (pregnancy has such a duration, counting from the date of menstruation).

Negele formula: 3 months are subtracted from the first day of the last menstruation and 7 days are added. For example, the last menstruation was May 10 - subtracting 3 months, we get February 10, and adding 7 days, we get February 17 - this will be the expected date of birth by the date of menstruation (we will assume that on February 17 the gestation period will be a full 40 weeks, and therefore, around this time, labor should begin).

Embryonic term(by date of conception or ovulation). The probability of pregnancy is maximum on the day when ovulation occurs - the process of release of a mature egg from the ovary. This usually occurs in the middle of the menstrual cycle (for example, if the menstrual cycle is 28 days, then ovulation occurs on the 14th day, and if the cycle is 32 days, then on the 16th day).

Considering that the egg is capable of fertilization within 24 hours after ovulation, and the life expectancy of the sperm is on average 72 hours (in some cases it can reach 4-5 days), the probability of fertilization is not 1 day, but much earlier - starting from 9 -10th day of the menstrual cycle (with a 28-day cycle). This circumstance greatly complicates the establishment of the expected date of birth by the date of conception. It is possible to set the due date for conception in cases where a woman knows exactly the date of ovulation (for example, she monitored basal temperature or, for medical reasons, ultrasonic monitoring of folliculogenesis, the process of egg maturation, was carried out). To determine the PDR, 266 days are added to the date of conception (since this is the true duration of pregnancy) or 38 weeks.

With a regular menstrual cycle (lasting 28 days), there is no difference between the calculations by the date of the last menstruation and the date of conception, therefore it is most convenient and informative to determine by the date of menstruation.

By date of first appearance in women's consultation. This method of determining the duration of pregnancy and childbirth will be as informative as possible if the expectant mother consults a doctor before 12 weeks of pregnancy. When registering, in order to verify the fact of pregnancy and establish its duration, the doctor will examine the gynecological chair to determine the size of the uterus. It begins to increase from 5-6 weeks of pregnancy, acquires a spherical shape. In addition, during pregnancy, the uterus becomes soft (outside of pregnancy, the uterus has a pear-shaped and dense texture).

Determining the size of the uterus during a gynecological examination, the doctor specifies which gestational age corresponds to an increase in the uterus. For example, at 5-6 weeks, the uterus becomes the size of a chicken egg, at 7-8 weeks - with a goose egg, by 12 weeks it reaches the size of a newborn's head and its bottom (the so-called upper part of the uterus) can already be palpated (palpated) through the anterior abdominal wall without resorting to vaginal examination. Starting from the second trimester, according to the height of the uterine fundus, one can approximately determine the gestational age: by 16 weeks, the uterine fundus is in the middle of the distance between the womb and the navel, by 24 weeks - at the level of the navel.

It is important to remember that the longer the gestational age, the higher the error in its determination by this parameter can be, since the height of the uterine fundus depends on many individual characteristics: the number of births in history, the size of the fetus, gynecological diseases (for example, with uterine myoma, the size this body will be more than the norm for a given period), the anatomical features of the body of the expectant mother, etc. Therefore, the examination performed before 12 weeks of pregnancy is of the greatest importance for determining the ED by attending the antenatal clinic - then the doctor will be able to determine the gestational age by the size of the uterus .

According to ultrasound. Determination of gestational age and estimated date of birth it can be done quite accurately if an ultrasound scan is performed in the first trimester of pregnancy (up to 12 weeks). When conducting an ultrasound examination at the earliest possible time (and it is possible to see the fetal egg by ultrasound from 3-5 weeks of pregnancy, the embryo begins to be clearly visualized a little later - starting from 5-6 weeks of pregnancy), the average inner diameter of the fetal egg and the coccygeal-parietal size are measured KTR of the unborn child. For each gestational age, there are certain KTR standards, measured in millimeters, by comparing which with the data obtained, it is possible to accurately determine the expected date of birth.

In the second and third trimesters gestational age is established based on the measurement of certain dimensions of the fetus: such as biparietal size (the distance between the parietal tubercles, or the large transverse size of the fetal head), head circumference, abdominal circumference, diameter of the thorax and abdomen of the fetus, length of the femur. The data obtained also make it possible to judge the gestational age, but it must be remembered that the larger it is, the greater the likelihood of error. This is explained by the fact that as the fetus develops, depending on the characteristics of the course of pregnancy, the presence of maternal diseases, hereditary factors, the size of the fetus, by which the gestational age is judged, will vary significantly. One mother will have a child weighing 2600 g and 48 cm tall, while the other will have 4500 g and a height of 57 cm, which is completely normal, since all people have individual anthropometric characteristics. Thus, it is possible to determine the gestational age as accurately as possible according to ultrasound data in I trimester of pregnancy or around 20 weeks, when there is the greatest match between fetal size and gestational age.

By date of first movement fetus. PDR can also be determined by such a parameter as the date of the first fetal movement. In this situation, it is more correct to talk about the date when the pregnant woman first felt the fetal movements, since the fetus begins to actively move in the uterus from 8 weeks of pregnancy, the mother simply does not feel this due to the baby being too small. It is believed that primiparous women for the first time feel fetal movements on average starting from 20 weeks of pregnancy, and multiparous women - from 18 weeks, therefore, to determine the expected due date for this parameter, 20 weeks are added to the date of the first fetal movement in primiparas, 22 weeks in multiparous.

It should be noted that this method DA definitions It is considered additional, or auxiliary, since fetal movements are a very subjective sensation, and besides, expectant mothers do not always celebrate it for the first time in the above terms. For example, primiparous women may first feel the movements of the fetus in the later stages of pregnancy - after all, this is still an unfamiliar sensation to them, and at first they may confuse it with intestinal motility or simply not notice it. Women with a pronounced layer of subcutaneous fat may first feel fetal movements 1-2 weeks later. Multiparous women, on the contrary, can notice the first movements at an earlier date (at 16-17 weeks), as they already know how it happens. These circumstances may reduce the accuracy of determining the expected date of birth by the date of the first movement of the fetus.

Why calculate the DA in multiple settings?

The need to calculate estimated date of birth by several methods simultaneously due to the following factors. First, despite the availability of state-of-the-art methods for estimating gestational age, it is almost impossible to predict when a woman will go into labor (within the accuracy of the day). Secondly, some of the data used to calculate the estimated date of birth may be uninformative for various reasons. For example, with an irregular menstrual cycle, the calculation of the EDD by the date of the last menstruation will not be accurate, and with a late first appearance at the antenatal clinic, the presence of gynecological diseases (uterine fibroids) or overweight, it will be difficult to determine the gestational age by the size of the uterus. Given these circumstances, the doctor sets the expected date of birth according to the maximum amount of data to clarify the time interval in which the birth is most likely to begin. As a result estimated due date most often defined not as one specific number (for example, January 15), but as a time period (for example, from January 12 to 17).

Nevertheless, even in the estimated term, which is correctly calculated according to all the data, far from all pregnant women begin, since the duration of pregnancy in each case depends on many factors. That is why the date of birth is called the estimated date.

Length of pregnancy, and therefore the period when regular labor activity develops, are individual, moreover, it is calculated based on the fact that childbirth will begin upon reaching the full 40 weeks, but the pregnancy is considered full-term after 37 weeks, so childbirth can begin in 2-3 weeks before the expected due date. A variant of the norm is the development of labor activity in the 41st week of pregnancy.

Thus, on duration of pregnancy and the date of delivery are influenced by many factors, among which an important role is played by the characteristics of the anamnesis - the age of the expectant mother, the number of previous births, the presence of miscarriages, premature births and / or abortions in the past, existing chronic diseases. In addition to these features, for a period onset of childbirth also influence the course of this pregnancy. For example, in a multiple pregnancy, childbirth often begins earlier than in a single pregnancy, and the gestation period is inversely proportional to the number of fetuses (the more fetuses, the shorter the period), which is due to overstretching of the uterus. With the development of placental insufficiency (pathology of the course of pregnancy, in which one or more functions of the placenta are disturbed, leading to insufficient supply of the fetus with everything necessary for growth and development), both the early development of labor and an increase in the duration of pregnancy by 1-2 weeks are possible.

Despite the impossibility of absolutely accurately determining the date of birth, it is still necessary to correctly calculate the EDD. Focusing on the expected term of delivery, the degree of biological readiness of the body of the future mother for childbirth (determined by the doctor according to a number of signs, one of the main ones is the degree of maturity of the cervix - the presence of biological readiness for childbirth is the key to the physiological course of childbirth and a favorable outcome for the mother and fetus) and the condition fetus, the doctor will be able to timely resolve the issue of the need for preparation for childbirth, prenatal hospitalization, drug treatment, etc.

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The online pregnancy calculator will help you calculate the gestational age, determine the expected date of birth, calculate the age of the fetus, and find out when the end of the first and second trimesters will come. The pregnancy calculator is a free service. Depending on the individuality of the organism, some data may not match.

Each pregnant woman keeps her own calendar, where she records all the changes that occur to her during pregnancy. However, the modern pace, a lot of family concerns do not always allow you to track on your own what week of pregnancy is going on and how the baby should develop. A pregnancy calendar comes to the aid of busy mothers: this is a complete description of all the changes that are happening at this stage with mom and baby. Thanks to this, a woman can easily track how much the baby weighs, what she should feel, what problems await her. But in order to find out how the child develops, you need to determine what the woman's gestational age is.

First day of last menstrual period:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Average cycle time (days):

22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

Calculation results

- Estimated date of conception

- Fetal age

- Gestational age

How to find out the time of conception?

Traditionally, in order to determine what the current gestational age is, a woman comes to the antenatal clinic in the clinic. The doctor conducts an examination, if necessary, prescribes an ultrasound and focuses on the last menstruation in the setting of the term. Based on this date, a calculation is being made when the mother should give birth.

But it is worth warning women that such a calculation will not always tell you the exact day of delivery. In medicine, there are two terms for determining pregnancy: obstetric and real. What is their difference?

The obstetric term helps to determine when the pregnancy began, based on the date of the last menstruation. In this case, the date of conception is not taken into account, since it is unknown to the doctor. The doctor proceeds from the concept of a woman's standard menstrual cycle, which lasts 28 days. Therefore, conception could occur during ovulation on the 14th day after the start of the cycle. It turns out the difference between the obstetric period and the embryonic period by 2 or even 3 weeks.

You can find out the real time more precisely if you undergo an ultrasound scan. However, ultrasound is prescribed no earlier than 10-12 obstetric weeks, and the woman's curiosity is much stronger.

How can you find out your own gestational age in order to subsequently focus on the calendar?

To do this, it is desirable to know the date of conception, or at least the possible days when this could happen. If you cannot set the date, you can use reusable pregnancy tests. The devices are equipped with sensors that determine the gestational age. The error of such devices is small.

You can calculate the gestational age on your own, based on the obstetric calculation method. But if this is difficult for you, an online calculator will come to the rescue. This is a program on the site that will calculate the approximate date of your ovulation and, therefore, the expected date of conception.

How does the calculator work, and what is needed for this? You just need to enter the first and last date of your period. The online calculator itself will calculate the middle of the term and determine the date of conception of your child.

If you know the date of conception, an online calculator will also help determine the time when pregnancy occurred. The way it works will be different. You need to enter the date of conception into the calculator, and it will calculate the gestational age by weeks. So you will know exactly which week goes on what dates you have, and you will be able to observe from the descriptions how your child grows.

When is the birth?

Now is the time to find out the due date. The same calculator that determined the date of conception will help you calculate the date of birth. The online calculation is based on the data on the date of conception or the last menstruation. In the latter case, you will know the due date based on the obstetric term.

If you know exactly how many weeks you have, then you can guess from when to expect the onset of labor. This usually happens at 38-40 weeks. Some women live up to 42 weeks: such a pregnancy is not considered post-term. It should also be noted that an error could occur when determining the gestational age. An online calculator can also make a mistake, as it calculates based on generally established observations. In addition, you could enter inaccurate data into it.

Practice shows that the date of birth is the date of the beginning of the last menstruation, to which 9 months are added. In these numbers, we should expect the completion of the family. But what to do if it is not possible to determine the period by menstruation, since the woman no longer remembers the exact date?

HCG analysis

If a woman does not follow the regularity of the cycle and does not remember the date of the last menstruation, the calendar is unlikely to help here. In this case, doctors recommend doing a blood test for hCG, a hormone that allows you to determine the presence of pregnancy even in the early stages.

HCG (chorionic gonadotropin) is produced in a woman only during pregnancy with a fetal egg. A biochemical blood test is able to determine its amount in the body and, on the basis of this, establish the presence and duration of pregnancy. The most informative are the first 12 weeks of pregnancy, when the level of hCG is still high. Gradually, it begins to decline, and a blood test will no longer give reliable data.

Approximately determine the size of the fetal egg, and according to it - what is the current gestational age, the doctor can also when examining the vagina and palpation.

Why do you need to know the exact date?

Not all women are attentive to their pregnancy and calculate the period by weeks. They think that it is the task of the doctor to calculate the gestational age in order to subsequently calculate the date of birth. During pregnancy, they do not think about how many weeks they have now, and how the baby should develop.

In vain, since no one better than the mother herself will determine whether the baby is comfortable inside. Dangers lie in wait for a pregnant woman at every turn, and it is better if she knows her due date by weeks. A calculator and a calendar can help with this, so it is not necessary to ask a doctor every time.

If you do not know how many weeks of pregnancy you have, open the calculator on the site, enter the required data, and you will receive an answer. It will help you remember the doctor's recommendations and warn yourself and your baby against possible complications. Isn't it nice to see in the photo and video how your baby is growing week by week? After all, you can only look inside with the help of ultrasound, but this happens only three times during the entire pregnancy.

The need to undergo screenings is another reason why a woman needs to know the exact gestational age. Studies, including a blood test for genetics and ultrasound, take place within strictly defined terms. If you do the analysis sooner or later, you can get an inaccurate answer.

Do not neglect the calculation of the gestational age by week. This will give the woman valuable material to determine if the baby is developing according to the norm, if there are any deviations, and what studies still need to be done.

What errors are possible?

Unfortunately, if the exact date of conception is not known, any weekly pregnancy calendar or conception calculator may not be accurate. The baby development calendar is based on the data that was originally determined. What if they are incorrect?

Unfortunately, errors cannot be avoided. According to statistics, in almost 20% of women during pregnancy, the difference between obstetric and embryonic terms is 14 days. If a woman's cycle is long, such as 35 days instead of 28 days, ovulation may only occur on day 21. Consequently, the difference between the obstetric term and the real one will be even greater. 1 week of the embryonic period will be equal to 5 or 6 obstetric weeks.

But even in the formulation of the embryonic period there is an error. It is several days, since the sperm can be stored in a woman's body for 3 days, so fertilization could not occur on the day of ovulation, but later.

Calculating the gestational age is a painstaking task. Not always a calculator and even a medical analysis can give an accurate answer. A woman should listen to her own feelings: they will help her find out by feeling what the gestational age is now, and how correctly the doctor determined it.

In order not to miss the fact of pregnancy and know exactly when fertilization happened, a woman should be attentive to the signals of her own body and conduct regular monitoring of her health. To do this, you need to keep a calendar where the dates of the beginning and end of menstruation, the facts of suspicious vaginal discharge (if any) will be recorded. This will allow you to establish the onset of the disease in time and avoid consequences for yourself and the child.

To be healthy and give birth to a healthy baby, a woman must be attentive to herself. The calculator on the site and the pregnancy calendar will help her with this!

When does a woman begin to be interested in the date of birth?

Then, when it comes time to prepare a dowry for the baby or when it comes time to go on maternity leave, to transfer all cases to colleagues for a while, and maybe much earlier, when only the expectant mother wants to influence the fate of her baby by planning his birth under a certain zodiac sign ?

One way or another, everyone is interested in determining the possible date of birth. In anticipation of changes in the composition of the family, you need to plan the time of holidays, the family budget, you may have to turn to future grandmothers for help.

From a medical point of view, the date of delivery is important when planning a caesarean section or for those women who will be calmer and more comfortable waiting for the moment of delivery in a hospital.

The abbreviation PDD means "estimated (planned) date of birth." It is worth paying attention to the fact that the date is precisely “estimated”.

No one can say for sure when your baby will decide to be born. But there are calculation formulas based on statistical data and the characteristics of female physiological cycles.

Many factors can affect the due date. Among them are the diseases of a woman, and the influence of ecology, and possible variations in the location of the placenta.

Important is the emotional state of the expectant mother and her age. But in the case of a normal pregnancy in a healthy young woman, the discrepancy between the actual date of birth and the calculated due date will be small (3-5 days).

Determination of the EDD by the date of the last menstruation

The Naegele formula, by which this calculation is made, is based on the fact that a normal pregnancy lasts 10 lunar months (280 days). Therefore, if a woman kept a monthly calendar and knew exactly their date, you need to count back 3 months, and then add another 7 days to the result:

EDD \u003d Date of menstruation - 3 months + 7 days

that is, if menstruation was on February 10, then counting back 3 months we get November 10, and adding 7 days we find out the PDR - November 17.

Calculation of EDD by ovulation

If you were planning a pregnancy and the date of conception, then you probably followed. allows you to determine. Adding 38 weeks (268 days) to this day, we get the possible date of birth.

ODD = Date of ovulation + 38 weeks.

How to calculate the estimated due date from the date of conception

If a woman knows exactly the date of sexual intercourse, which resulted in conception, another way to determine the date of birth can be offered. Physiologically, it is based on the same cycle as the basal temperature calculation, but does not require any preliminary measurements and charts.

EDD = date of conception + 266 days

That is, if sexual intercourse occurred on March 10, the expected date of birth will be November 22. The error of this formula is 3-5 days, it is associated with the period of life of a spermatozoon in a woman's body.

Determination of PDR during a medical examination is the most accurate method

If a woman registers for pregnancy in the early stages, then the condition and size of the uterus, the doctor will determine the duration of pregnancy and the approximate date of its completion (based on the "average" period of 40 weeks).

For a short period, the uterus is not yet palpable through the outer abdominal wall and a manual obstetric examination can tell about the period. But its characteristics are very subjective and depend on the qualifications of the doctor.

At 4 weeks, the uterus is the size of a chicken egg, by 8 weeks it will be larger - like a goose egg, and by 12 weeks it will reach the edge of the pubic bone.

An experienced obstetrician-gynecologist can determine the gestational age from these data.

Note that this technique works most accurately at the beginning of the first trimester. If a woman is not in a hurry for the first medical appointment, then there may be an error related to whether a large fetus is expected to appear, whether there is polyhydramnios, etc.

Planning the date of birth based on the results of ultrasound

During an ultrasound examination, it is possible to accurately determine the size of the fetus and its maturity. This will allow you to guess the date of birth.

Moreover, if you go for an examination in the first trimester and the gestational age is determined by the size of the fetal egg, then when you repeat, the doctor can tell you other data. This is not due to a mistake, just the intrauterine development of the baby is uneven.

The closer the due date, the more accurately you can determine the readiness of the child for birth.

For example, to plan hospitalization, preparation for a caesarean section.

Determination of the PDR by the date of the first movement

This method is less accurate than the previous ones, but is also physiologically justified.

All other formulas: calculation by the date of menstruation, ovulation or movement, are based on a standard 28-day cycle.

If a woman's menstrual cycle is less or more than 28 days, her physiological and metabolic processes may not fit into the calculated time frame. Moreover, there is not always a direct relationship here (that is, a woman who has a cycle of 25 days should not subtract 250 days from the date of the last menstruation instead of 280.

In any case, the calculation is carried out according to the standard formula. Just keep in mind that in your case, the likelihood of a baby being born a little earlier than the expected date increases).

The method with the greatest error - calculating the EDD by the date of the first movement - is further complicated by the fact that not every woman can accurately determine the moment of the first movement. The movements of the child are often mistaken for peristalsis or gases.

In addition to the objective calculation error, the date of birth can be affected by:

chronic diseases of a woman;
bad habits;
heredity;
or multiple pregnancy;
mother's age;
a cold or bacterial infection already during pregnancy;
repeated births;
fetal pathology;
stress.

As soon as she finds out about the pregnancy, the woman is already interested in the expected date of birth. After all, by this moment you need to prepare a dowry for a newborn, if necessary, provide yourself with assistants or pick up a nanny for older children, plan a family budget, taking into account replenishment of the family and a long vacation for the mother.

Someone is in a hurry by the time the baby is born to improve living conditions, make repairs or move closer to relatives. And all these issues need to be resolved by a specific date, the DA.

The methods for calculating the date of birth were very relevant, the calculation formulas were developed by obstetricians in different countries. With the advent of ultrasound, other methods with a large error began to be used less frequently. But they still arouse the interest of those who want to make a calculation without consulting a doctor, or at the stage of pregnancy planning.

SUPPLIED
DATE OF DELIVERY

FIRST DAY
LAST PERIOD

Last day of menstruation: Estimated due date: Left before delivery: Zodiac:

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

Using our gestational circle is very simple.

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

green arrow

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

arrow "today"

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

arrow PDR

What does "gestational" mean?

Many hear this word for the first time in a antenatal clinic. The Latin gestatio literally translates as "bearing." Therefore, "gestational" means "pertaining to pregnancy."

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

Gestational disc for determining due date

There are different calculators, the main purpose of which is to establish the date of the baby's appearance. Gestational circle- an indispensable tool for preparing for childbirth and better control of 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 delivery and, as it approaches, carefully monitor the signals of the body.

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

The gestational circle is one of the most informative calculators. In addition to the estimated 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 what sign of the zodiac and in the year of which animal according to the eastern calendar a child will be born. For some couples, it helps to choose a name.

How is the gestational cycle

With this visual calculator, it is easy to determine the due date and track the height and weight of the fetus during pregnancy. The outer disk 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 scale of weight, and at the last level - the growth of the fetus.

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

How to use a gestational disc to determine the gestational age

The gestational circle is used by many obstetrician-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 to determine the expected date of birth as accurately as possible. To calculate the gestational age according to the gestational circle, it is enough to move the thin green arrow to the date of the start of the last menstruation. The PDR arrow will indicate the date of delivery, provided that the pregnancy ends at 40 weeks. Using the “today” arrow, it is easy to track the average height and weight of the fetus for each week.

For example, the last menstruation was from 12 to 16 December. For the calculation of the gestational circle, only the first date is important - December 12. Set the thin green arrow to this number. Twisting the arrow, pay attention to the center of the circle. This is much more convenient than peering into 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 from September 18th.

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

To independently determine the date of birth of a child in this case, the gestational circle will be ineffective. Usually, doctors prescribe a blood test for hCG. Chorionic gonadotropin is a hormone that is released in the body of a woman after implantation of the embryo in the uterus at 4 obstetric weeks. From this point on, you can get the most reliable results.

When using the strip test at home, the second strip may be translucent. This indicates either the unsuitability of the test, or a small amount of the hCG hormone in the body. To obtain reliable results, you need to try again in a week if menstruation does not begin. A weakly pronounced second strip can appear in women taking hormonal drugs, regardless of pregnancy.

A home test only shows the presence of pregnancy. According to the result of a biochemical blood test, its duration is determined. Don't put off checking. Analysis for hCG is most reliable in the first 12 weeks. Gradually, the level of the hormone decreases, and at a later date it is difficult to determine the time of conception.

When the week of pregnancy is known, the gestational circle can be used to calculate the date of delivery 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 last menstrual period.

Errors

Bearing a fetus is a complex process that each woman proceeds in a special way. Moreover, the course of the first pregnancy does not mean that the next ones will follow the same scenario.

The pregnancy calculator allows a certain error. In addition, when setting the initial data, errors are not ruled out. The accuracy of the calculation depends on the individual characteristics of the organism. The pregnancy wheel shows the most accurate result with 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 terms.

In addition, the error can be provoked by inaccuracy in determining the embryonic period. The spermatozoon is able to remain 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 body of the expectant mother, the error in calculating the expected date of birth often reaches 2 weeks. Ultrasound gives more accurate results, although the method of calculating the beginning of the last menstruation is recognized worldwide as one of the best.

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

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

Some 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 could not occur. The moment of conception depends on ovulation and varies within a couple of weeks.

With a standard menstrual cycle of 28 days, ovulation 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 the dates of birth according to various calculations do not match. Which one to believe?

In official medicine, it is believed that embryos develop in the same way during the first trimester. On ultrasound, the gestational age is determined according to the table of correspondence between the size of the fetus and a certain period of development. For example, the calculation for the last menstruation shows the result of 12 weeks, and the diagnostician calls 11 weeks. More reliable is considered to be the period set during the first ultrasound. In this example, the difference is due to early ovulation, but it can be late. For the doctor, the result of an ultrasound examination is a priority.

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

The gestational circle gives an idea of how the unborn child develops 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 an average of 71 g. It is interesting for every woman to know how the fetus changes. With the gestational circle, observation becomes simple and even more fun.

The most important weeks of pregnancy

In order for the fetus to develop correctly and the child was 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 feel the conception, or from the first weeks obvious signs will appear in the form of a heightened sense of smell, morning sickness, etc. It is not uncommon for a woman to find out about pregnancy only by her enlarged belly.

For pregnant women, the following factors are of particular danger:

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

When to be extra careful

Critical periods coincide with the phases of active growth 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 insidiousness of the first weeks is that a woman may not be aware of pregnancy. As a result, the prerequisites 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 increase with the fetus.

The period from to 22 weeks is considered the most important. At this time, the unborn baby is most active. The biggest 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 as similar as possible to a baby, but it is not yet able to survive separately from the mother's body. Causes of preterm labor may include 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 on the gestational cycle. This is due to the fact that they do not have to be difficult at all. The more you focus on the dangers, the stronger the destructive effect of stress. You can use the pregnancy wheel during the entire period of gestation. On the diagram, it is convenient to track 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 a future mother. The calculator is a circle, similar to a watch dial, the inside of which can be rotated, setting one or another hand in 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 determine the date of future births by the arrow "PDR", and by the arrow "today" you will find out what week of pregnancy you are now, and what is the height and weight of the fetus on present day. The Pregnancy Wheel can also be used in other ways. For example, if the birth has already taken place, then you can set the arrow "Ed" (estimated date of birth) so that it points to the day of delivery. Then a thin green arrow will show you the date on which you had your last period before pregnancy. Among other things, the calculator determines the zodiac sign of the unborn child, and even his zodiac animal according to the eastern calendar.

Finding out the date of birth is the natural desire of a woman carrying a baby. This helps to better prepare for the birth of a child and mentally tune in to the process of childbearing. If there are several ways of how to calculate the due date yourself.

The estimated due date (EDD) is the date when labor should begin after forty weeks of gestation. These are approximate figures, since thirty-seven weeks is the period from which a pregnancy is considered full-term. A baby can be born at forty-one weeks and even at forty-two weeks, and this is also considered a normal period, but usually doctors do not allow the expectant mother to pass so long and stimulate labor artificially.

Not a single specialist, including the most highly qualified doctor, can name the exact date when labor activity will begin.

The time of the birth of the baby is largely influenced by the individual characteristics of the expectant mother and the condition of the baby. For this reason, the day of birth can only be calculated approximately.

There are several methods for calculating the day of delivery. It is recommended to use all methods at once in order to compare the results later.

By date of conception

This method can only be used by a woman who is sure on which particular day of intimacy the conception occurred. The calculation of the approximate date of the birth of the baby is carried out according to the formula:

"Day of conception + 266 days = day of birth."

To the received date, you need to add 3-5 days or subtract the same amount. This error is due to the fact that the seed of a man can be viable in the body of a woman for a week.

If pregnancy occurred on this day, then the estimated date of the baby's birth is calculated by the formula:

"Day of ovulation + 268 days = date of birth of the baby."

The error is also 3-5 days.

By last menstruation

When calculating the due date for the last menstruation, two methods are used.

280 days are added to the first day of menstruation. The resulting date will be the estimated date of birth. The essence of this calculation is that the difference between the beginning of the cycle and the day of ovulation is two weeks.
According to the Negel formula. It is based on the fact that the period of bearing a baby is 280 days. According to this, in order to calculate the expected date of birth of the baby, it is recommended to subtract 3 months from the first day of menstruation, and a week is added to the result. On this day, exactly one year later, the birth should take place, given the error of a few days.

The use of any of the options is relevant only when a woman has a regular cycle. If menstruation begins at different times, then the data obtained will be inaccurate with an error of thirty days.

Health care providers usually use the second method when calculating the due date.

An ultrasound scan shows the day when ovulation occurred, as well as the gestational age. This is one of the few ways that determines the exact date of pregnancy to the day. To do this, it is recommended to conduct it in the first trimester. Knowing the period, the date of ovulation or menstruation is determined. This allows you to calculate the estimated date of birth of the baby in several ways.

The ultrasound itself can also provide information about the day of delivery. For this, the procedure is carried out after the 20th week of pregnancy. In this case, the specialist clearly sees at what stage of development the fetus is, and can determine when it is time for the baby to be born.

If during an ultrasound examination it turns out that the baby began to develop faster, then the specialist may go astray in the calculations. In this case, he states that the term for bearing the baby was incorrectly determined and moves the date of the onset of labor.

By the first movements

If the expectant mother was able not to miss the time of the first stirring of the baby, confusing it with the natural processes occurring in the intestines, then she can calculate the date of the birth of the child from this moment.

According to statistics, the baby begins to move after the 20th week of conception, if the pregnancy is the first. If the mother bears the baby for the second and subsequent times, then the child will make itself felt after the 18th week. As practice shows, a woman can feel the first movements ahead of schedule by 14 days. This also happens two weeks later than the due date. For this reason, the error in calculating the approximate date of birth is plus or minus 14 days.

To find out using this method, what date the child should be born, during the first pregnancy, 20 weeks are added to the date of stirring. If the mother has a second birth and subsequent ones, then 22 weeks are added to the date. The resulting figure will be the estimated date of the onset of labor.

Following a gynecological examination

An experienced doctor, based on the results of the examination, can determine what date a woman should give birth. The specialist builds his assumptions on the basis of the size of the uterus and its condition. The technique is relevant only in the first trimester of pregnancy.

If a woman arrives later than this period, even a gynecologist with extensive experience will not say when the baby will be born, since the size of the uterus varies for each woman in different ways. The dimensions of the organ are influenced by the individual characteristics of the expectant mother and a number of other factors.

When determining the expected date of delivery, the doctor is based on the duration of the pregnancy at 40 weeks. This is the average rate of bearing a baby.

In the early stages of conception, a gynecological examination does not provide data on when labor will begin. This is due to the fact that the uterus is not palpable through the abdominal wall during external examination. In this case, the term of delivery helps to determine the obstetric examination. Such data are also approximate, since the result depends on the inner feelings of the doctor and his experience.

As clinical studies show, when pregnancy reaches four weeks, the uterus becomes the size of a chicken egg. At the eighth week of gestation, the dimensions increase to the size of a goose egg. At the twelfth week of pregnancy, the uterus enlarges to such a state that it reaches the edge of the pubic bone.

In this way, the doctor will determine the date of the baby's birth only in the first trimester. If the expectant mother applied at a later date, she is advised to use other methods to correctly determine the date of birth.

Which method is considered the most effective

Ultrasound is considered the most effective method for determining the date of onset of labor.

It shows the state of the placenta, how the baby's head is located relative to the entrance to the small pelvis, the level of development of the child and the size of the opening of the cervix. Having compared all these factors, the specialist names the term of bearing the baby as accurately as possible, and already, based on this, the date of birth is calculated.

Another effective method of counting the onset of labor is an examination by a gynecologist. This method provides relatively accurate information if you contact a specialist in early pregnancy.

Gynecologists often determine the date of the expected birth by menstruation. They use Nagel's formula for this. To use this method of counting, the doctor should ask the expectant mother whether she has regular periods or not.

If the answer is negative, the specialist is obliged to use other methods of calculating the number of onset of labor, otherwise an inaccuracy may be made, which will lead to the onset of labor outside the hospital or the woman's stay in the maternity hospital for too long.

Other methods can be used as additional ones for the most accurate calculation of the day of birth.

Why DA setting results are considered approximate

According to statistics, only 5% of women in labor have babies born on the date that they calculated or were named by a specialist. No method has been developed to determine the exact day of delivery. Each of the methods has an error of 3-5 days and even two weeks.

Ultrasound can also be inaccurate if the baby has taken an uncomfortable position in the uterus. Deviations in timing provokes multiple pregnancies. In this case, several factors are compared in order to at least approximately understand when the birth of children will take place.

The following factors influence the date of the birth of the baby:

age of the expectant mother;
pathologies that a woman suffered during the period of bearing a baby or diseases in a chronic form that arose before pregnancy;
location of the placenta;
ecological situation in the region of residence;
state of the nervous system;
harmful addictions;
dimensions of the child and multiple pregnancy;
the level of development of the child;
repeated pregnancy;
heredity.

The main moment that affects the onset of labor is the course of pregnancy. If there are no complications, then labor may begin a few days earlier or later than the expected date of birth. The discrepancy is usually 3 to 5 days.

Conclusion

How to calculate the due date as accurately as possible? Unfortunately, even a specialist can only give an approximate date for the birth of a baby. But even such data is usually enough to morally tune in to childbirth and prepare for this day all the essentials for the baby.

Online services have appeared on the Internet, in which women are offered to enter some information and find out the date of birth. This method is also only approximate, it is not recommended to rely on it with 100% certainty.