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

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

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

During the first visits to the antenatal clinic, the obstetrician-gynecologist usually determines the estimated date of birth (PDD). There are several ways to do this.

Method 1. The method of determining the date of birth by the date of the last menstruation

This is the most common way to calculate the DA. Subtract three months from the start date of your last period to calculate your due date. You need to add 7 days to the resulting date - this number is the very expected date of birth. Obstetricians-gynecologists, when calculating the PDR by this method, usually use special obstetric calendars, which greatly simplify the calculations.

However, it is far from always possible to accurately calculate the PDR using this method alone. This happens when a woman has irregular periods, or those patients who have a regular but long menstrual cycle. For example, if a woman has a typical cycle duration of 35 days (and not 26-28, like most), then most likely, she will be able to conceive only on about the 21st day of the cycle (and not on the 14th, as with a 28-day cycle). Accordingly, your period-based PDE will be one week earlier than your actual estimated due date.

Method 2. ovulation date or conception date

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

Method 3. Method of determining the due dateon the first visit to the antenatal clinic

Usually, the date of the upcoming birth and the gestational age are calculated by the doctor when registering for pregnancy. Doctors call this method of calculation - according to the "first attendance at antenatal clinic". The duration of pregnancy, and, accordingly, the date of delivery in this case is determined by the following parameters - the size of the uterus and the level of chorionic gonadotropin in the blood. Examining a woman in a gynecological chair, an obstetrician-gynecologist with both hands determines the size of the uterus. Most accurately, this method "works" for early dates pregnancy, up to about 12 weeks. The earliest term that can be determined by the size of the uterus is 5 weeks of pregnancy. By this time, the uterus enlarges slightly, softens and becomes rounded. For more later dates the size of the uterus may vary slightly depending on the size of the fetus, the amount amniotic fluid, the structure of the woman's pelvis.

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

Method 4. The method of determining the date of birth n about ultrasound

When conducting an ultrasound scan in early pregnancy, by measuring the size of the ovum and embryo, the gestational age can be determined with great accuracy. At 4-5 weeks in the uterus during ultrasound examination, a small "black circle" is determined - this is a fertilized egg, in which an embryo will appear a little later. At about 6-7 weeks, an embryo appears in the form of a small "strip", and you can see its heartbeat. More accurate is the period calculated by measuring the CTE of the embryo (CTE is the coccygeal-parietal size, that is, the maximum distance from the head of the fetus to its coccyx). After 12 weeks, the gestational age with ultrasound is determined by measuring various sizes of the fetus's head and abdomen, the length of its arms, legs, etc.

Up to 9-10 weeks of pregnancy, the embryo grows proportionally, and its size in all women with the same gestational age will be approximately identical. In the future, these indicators will differ in expectant mothers. of different nationalities, with different body weights, the weight of mom and dad at birth will also matter, and so on. That is, in the later stages of pregnancy, normally developing babies of the same "age" can have different sizes (fluctuations can be about 2 weeks and sometimes even more), and in such a situation, it is impossible to reliably determine the gestational age according to ultrasound data.

Method 5. The method of determining the date of birth nabout the first stirring of the fetus

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

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

All of the above methods allow you to calculate the expected date of delivery. However, it must be remembered that, of course, it is not completely accurate. Overweight or undermaturity of pregnancy is not uncommon. Abnormalities in fetal development, pathological processes in the body of the expectant mother, stressful situations, hereditary factors and many other reasons can provoke the onset of premature labor. Therefore, it is very important to realize that calculating the date of birth is a very conditional concept, regardless of the method used, and it is not possible to predict exactly when the baby will be born.

How is the estimated due date of IVF calculated?

In the case of IVF (in vitro fertilization), fertilization of an egg with a sperm is performed "in vitro" by an embryologist. Embryos develop in the laboratory for 3-5 days, after which they are transferred to the uterus. Doctors calculate the true gestational age after IVF from the date of ovarian puncture, that is, procedures when the follicular fluid and the follicles contained in it are taken with a special needle for subsequent fertilization "in a test tube", and to determine the "usual" obstetric period, add 2 weeks by the date of ovarian puncture.

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

Menstruation is delayed, and in the tests two cherished stripes appear more and more clearly? It's too early to go to the gynecologist, but do you really want to know when the baby, who seems to have already settled in your tummy, will be born? In this case, use the help of our service to calculate the due date.

Calculate due date online

There are several methods for calculating the expected date of birth. They are all based on the fact that normal pregnancy lasts on average about forty weeks, counting from the beginning of the last menstrual bleeding. The expected due date will fall on the day after 280 days or 40 weeks after the last period began.

Calculating the due date on our service is very easy, convenient and fast - it only takes a few minutes or even seconds. To do this, you need to fill the calculator windows with numbers corresponding to the date of the first day of your last menstruation in the following format: day, month, year.

In just a moment, the calculator will calculate and display the result on the monitor.

This service works on the principle of calculating the duration of pregnancy, which in most cases lasts for 40 obstetric weeks or 280 calendar days... The date of birth can be calculated independently, if by the day when your last menstruation began, add required amount days / weeks. But with this handy calculator, calculations are made easier, faster and without errors. However, you should understand that this is only an approximate, approximate date when you are expected to give birth. The duration of pregnancy is influenced by a large number of factors, therefore it is different women may last for an unequal period of time.

Calculate due date by date of conception

If you reliably know the day when fertilization occurred, then the calculation of the date of birth by the date of conception will be even more reliable. To find out when the baby will be born, it is necessary to add 280 days to the day on which the coveted sexual intercourse took place.

It should be understood that the date of sexual intercourse (even if you are almost one hundred percent sure of its authenticity and even if this month you had only a single case of sexual intercourse) is not always the date of conception of the child. The thing is that ovulation (the release of an egg ready for fertilization) can occur in a day or two or even more after sex, but sperm that have entered the vagina earlier can wait for this moment to merge with the egg and form a new life. Thus, the calculations can turn out to be wrong within a few days. But still, the date of conception can be determined approximately.

You can also calculate the expected date of birth by the day of ovulation. If you keep an appropriate schedule, then the calculations will be quite accurate. But you can calculate that very day roughly, even without knowing the exact date of ovulation. It is believed that the egg matures around the middle of the cycle. With a 28-day menstrual cycle, this moment occurs on the 12-15th day. By adding 280 days to the day of the expected ovulation, you can calculate the date of birth.

Well, having received the result, proceed to pleasant troubles and do not forget to visit the antenatal clinic in time, where you will be followed up for the next nine months.

How many women give birth, the same amount of time there is no dispute among expectant mothers about how to determine the date of birth of a child. The difference between your own calculations, the ultrasound readings and the doctor's notes is completely confusing. How to determine the due date? Let's try to figure it out, because even in old books about obstetrics there are calculation schemes, and modern medicine should know this all the more.

How to calculate the due date - is there an exact way

Modern technologies provide women in labor with the opportunity to correctly determine the moment of birth of a baby in several ways:

• Obstetric, which is calculated according to the last menstruation.
• Primary fetal movement.
• After visiting the gynecologist, who sets the date based on the examination.
• Fetal, which is determined by the date of ovulation.
• Based on the results of an ultrasound examination.

In addition to the above methods, women in labor determine the required time frame with a special online calculator. With so many different ways of determining pregnancy, doctors calculate with accuracy the baby's birthday according to statistics only in 4 cases out of 100, because the duration of gestation is influenced by a lot various factors, and heredity - in the first place.

The obstetrician community recognizes a full pregnancy not only at 40 weeks, but also at 38 weeks, so the due date always moves two weeks in two directions. An experienced gynecologist sometimes determines the day of birth by the shape of the expectant mother's abdomen, but this method is effective only immediately before childbirth. Let's consider each option for determining the due date separately.

Determining the term of labor by menstruation

This is an old calculation method, but it is only suitable for those women who have a regular cycle. If menstruation sometimes comes with a delay or earlier, then there will be large discrepancies in the calculations. The easiest way is to determine how much time has passed since conception. Remember how many days have passed since the first day of your period? The total number of days counted will indicate the duration of the fetus.

Much more precisely, the term is determined by the Keller formula. If 280 days are added to the first day of the last menstruation, then the approximate birthday of the baby will be released. Where does the number 280 come from? The average number of the sum of the life expectancy of the fetus and the period that passes before ovulation is taken. The average includes the following indicators:

• the period from conception of a child to his birth (266 days);
• average menstrual cycle (28 days);
• ovulation period (14 days of the menstrual cycle).

The obstetric period is equal to the average duration of the menstrual cycle, therefore, when calculating, gynecologists are guided by the indicators of the obstetric calendar and by 280 days. The lifespan of a sperm is several days, so even if the time of intercourse is known, it is impossible to determine exactly when ovulation occurred. A baby is considered full-term if it was born between 38 and 42 weeks, so the error of this method is also two weeks. Using a special table shown in the photo below, the obstetric gestational age is determined.

Calculation of the due date by the date of conception

It is very easy to determine the moment of birth by the day of ovulation or the date of conception. Organism healthy woman is able to conceive a child only on certain days of ovulation, when the egg is ripe and leaves the ovary. If the menstrual cycle lasts 28 days, then ovulation happens exactly in the middle of the cycle. Many women say that they feel the moment of ovulation, so it is easy for them to predict the date of birth: at this moment, bloody, not abundant discharge from the vagina begins, libido increases and the heaviness in the lower abdomen is felt.

How to determine the exact due date if you know the day of ovulation? To do this, add 280 days to the middle of the menstrual cycle. In the same way, the term of delivery is determined by the day of intercourse, if it was a single one. But here there is a high probability of inaccuracy, since sperm cells live for several days. So, if intercourse was on the 14th day of the cycle, then conception occurred on the 16th or 17th day.

Determination of the term of labor by the first movement of the fetus

This method has existed for many centuries, but this does not prevent it from being in demand. And if only a few modern women in labor determine the due date in this way, then when there was no diagnostic equipment, all women used it. The first fetal movement usually marks exactly the middle of pregnancy, therefore, the due date is counted from this date. But experienced obstetricians doubt the accuracy of this method, and they have several reasons for this:

1. A thin girl leading a sedentary lifestyle feels fetal movement much earlier than planned.
2. Primiparous women usually feel the first tremors a couple of weeks after those who give birth again.
3. In fact, the baby in the womb begins to move at the 12th week of pregnancy, but mothers still do not feel this.

For these reasons, the method of determining the child's birthday by the first stirring cannot be called accurate. The error is especially large if the fetus ripens 41 or 42 weeks, which is considered quite normal. So that the doctor and mother do not make the wrong decision in relation to the fetus, there are more accurate ways to determine the duration of pregnancy, for example, an ultrasound examination.

How to find out the date of birth using an ultrasound scan

Even an experienced specialist will not tell a future mother a 100% exact date of birth of a child. The term of labor is, at best, indicated with an accuracy of several days, because to a greater extent it depends on the woman in labor herself: her emotional state throughout the pregnancy and physical health... As statistics show, the method of ultrasound examination is very popular today. Greater accuracy of the examination is achieved for a period from 6 weeks to 12. Ultrasound is also ineffective in the later stages, as in the earlier ones.

In the later stages, even with the help of an ultrasound scan, it is impossible to determine the exact birthday of the child. After all, everything is individual: some babies are born with a weight of 5 kg, others weigh a little more than 2 kg at birth. Also, studies in the field of obstetrics and gynecology show that small women often give birth to large children and, conversely, large women in labor give birth to children up to 2 kg.

The specialist determines the age of the fetus by the size of its head and limbs, and based on the size abdominal cavity the mother, the exact size of the embryo, the condition and size of the uterus, the doctor calculates the approximate time of birth in any month of pregnancy. In any case, the results ultrasound examination both doctors and expectant mothers believe in the first place.

Date of birth determination table

There is one more efficient way determine the approximate date of birth - by weight gain. For the entire period of pregnancy future mom gains an average of 9 kg to 14. If twins are expected, then the gained weight reaches 21 kg. In the first trimester, the weight practically does not change, in the second, she gains about 1 kg per month, and already in the third trimester, a woman is gaining weight rapidly - up to 500 g in one week.

Guided by a special table for determining the timing of childbirth, by weight, you can check the readings of the numbers during weighing. Obstetricians begin to use this table from the 7th month of pregnancy, when the expectant mother is actively gaining weight. According to the information on this scale, a woman should gain about 20 g per week per 10 cm of height. Based on the total body mass index, female figures are divided in the table according to the following types:

• Lean - up to 19.8 (group 1)
• Medium build - from 19.8 to 26 (group 2)
• Obese - from 26 (group 3)

Special preparation is needed for this day. There is so much to buy, cook, study a huge amount of literature, think over all possible scenarios for the development of events. And we, women, think that it would be a shame not to take into account something.

All pregnancy is not only a spiritual attitude, but also quite material chores that should be carefully planned.

In a simple formula due date calculations 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.

It's simple - exactly in the middle of the menstrual cycle, i.e. after 12-16 days from the first day of the last menstruation.

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

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

Let's assume that conception took place in the middle of the last menstrual cycle, from which 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 an "estimated" secret date. This is not true, since pregnancy lasts a little longer - approximately 280 days or 40 weeks.

True, the doctor quickly eliminates this error and helps the patient to determine 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 obtained is the estimated period childbirth, which your gynecologist will enter on the card.

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

But you cannot focus only on these calculation systems, because for some, a full-term pregnancy can last 38 weeks, and for others - 42, all this is within normal limits.

Multiple pregnancies, as a rule, end earlier than the date calculated by the doctor.

How to correctly calculate the term of labor by perturbations. Folk omens

To determine the due date, you can use popular sign, which for many centuries, even before the development of medicine, helped expectant mothers.

Exactly in the middle of pregnancy, primiparous women first feel the movements of their baby - this significant event usually occurs in 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, in the second / third / fourth time, intrauterine movements are perceived better.

By the time the intrauterine movements begin, 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 complexions feel tremors at different weeks, a thin woman feels movements within 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 assess the incomprehensible movements within themselves - some confuse this action with an intestinal disorder, sorry, or the movement of the abdominal muscles (weak convulsion).

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

We calculate the term of delivery by ultrasound

Another method for assessing the due date is computer diagnostics, or, more simply, ultrasound. In the early stages (up to 12 weeks), ultrasound can determine the day of conception with an accuracy of the day, based on the size of the head and trunk of the embryo.

Until a certain point (about 3-4 months of pregnancy), all babies develop in the same way, after which the genetic predisposition, dietary habits and lifestyle of the mother are already affected.

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

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

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

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. You should focus on your feelings and nature, which is never wrong.

In this article:

The estimated date of birth begins to interest a woman from the first day she found out about her situation. The approximate birthday of a child can be calculated in several ways, but none of them can boast of 100% accuracy. Many factors can influence the pregnancy process, and labor is often premature or late.

What determines the term of delivery

Even in a healthy woman carrying healthy baby, the due date may deviate from the estimated date and depends on:

• from whether she gives birth in or;
• from the duration of the menstrual cycle;
• from heredity and others individual characteristics mothers;
• from the features of the intrauterine development of the baby;
• on how many children are in the womb.

In the presence of chronic diseases in a woman, impaired intrauterine development of the child, acute diseases or injuries during pregnancy - the due date can deviate significantly from the planned date.

Methods for determining the date of birth

The most common methods for determining the expected due date are:

• by the date of the last menstruation;
• by the time of ovulation;
• by date of conception;
• by ultrasound;
• by the size of the uterus;
• by the first movement of the fetus.

Let's consider each in more detail.

By the date of the last menstruation

The date of birth by menstruation is the most common way to determine.

It has been used by obstetricians and gynecologists for many decades because:

• not all pregnant women know the time of the last ovulation or the date of conception during regular sex life, but everyone remembers when they had their last period;
• this is a fairly accurate method.

To determine the day of birth, you need to remember the first day of the last menstruation, add 1 year to this date, then subtract 3 months, and then add 1 week. The calculated date will be a guideline for the expected birth. Another way of determining: add 9 months and 1 week to the first day of the last menstruation.

By the time of ovulation or anticipated conception

The method of calculating the date of birth by the date of conception can be used with a planned pregnancy, when a woman has specially calculated the days of ovulation and knows them. It is during this period that conception occurs. To the first day of ovulation, add 266 days and calculate the date of delivery according to the calendar. This method is called embryonic.

By date of intercourse

This method is convenient to use with irregular or rare sexual activity. In this case, the woman knows which day in her life was decisive. It's very simple - 266 days are added to this date. This method is closer to embryonic. The dates of birth calculated in these two ways can differ by only a few days, because the dates of intercourse and conception often do not coincide. Not everyone knows that some sperm are able to live in a woman's body for up to 9 days, waiting in the wings.

By ultrasound

Using an ultrasound scan, the doctor can determine the approximate date of delivery, based on the established age of the fetus. Most accurately, this is established in the first trimester of pregnancy. In the future, there may be an error from several days to 3 weeks.

Largest uterus

The ancient medical method was the approximate determination of the duration of pregnancy and, accordingly, the expected birth by the size of the uterus. As in the previous case, you can more accurately determine the time of delivery in the early stages of pregnancy. In the future, the size of the uterus depends on many factors (the size of the fetus, the amount of water). In addition, this method is only suitable if there is 1 baby in the uterus.

At the first movement of the fetus

Antique folk way guessing the due date is wiggling the baby. After the disappearance of menstruation, a woman could only suspect about the presence of pregnancy, but when the fetus began to move, this was an absolute sign.

The woman added 20 weeks to this date and could quite accurately guess the due date with minor errors. It should be borne in mind that multiparous are already familiar with the feeling of fetal movement in the uterus and they usually feel it 1-2 weeks earlier than primiparous.

Efficiency of calculations

The exact day of delivery cannot be determined, because the normal time for delivery is between 38 and 42 weeks of gestation. Thus, as many as 28 days can be considered the date of delivery "on time". However, in the normal course of pregnancy different ways calculations roughly coincide and circle around one date in the range of +/- 14 days.

Gynecologists still officially use the calculations for determining the possible day of birth by the last menstrual period, therefore this period is called obstetric. This method in about 20% of cases guesses the date of birth with an accuracy of +/- 5 days, and this is a fairly high percentage. The exact coincidence of the date of birth and obstetric term is about 5%.

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

Regardless of the duration of the menstrual cycle, the obstetrician-gynecologist applies the formula for calculating the due date by the date of the last menstruation. Accordingly, women with a short cycle and a long one will have the same due date. However, the date of ovulation is different for them, therefore, conception and due date will be different.

With a short menstrual cycle (24 days) ovulation occurs on the tenth day. Fertilization takes place on the days of ovulation. Therefore, the actual term in women with a short cycle will be expected a week earlier. The due date is calculated using the following formula: the date of the first day of the last period plus 1 year and minus 3 months.

Long cycle (35 days) ovulation occurs on the twenty-first day. The birth will be a week later than the gynecologist calculated. A woman can calculate the date in this way: the date of the first day of the last period plus 1 year, minus 3 months and plus 14 days.

Calculate the date of birth with an irregular menstrual cycle with large jumps follows the classic formula.

When you can't use the obstetric calculation method

The obstetric method of determining the date of birth by the last menstrual period is the most common.

But it is not possible to use it in the following cases:

• when pregnancy occurs immediately after the previous birth, and there has been no menstruation yet;
• with severe menstrual irregularities, when the interval between periods can be more than several months, as is the case with menopause or various female diseases, for example, polycystic ovary disease or hormonal disorders.

What can be deviations from the terms

Carrying a baby lasts 9 calendar months, or 10 lunar months (28 days each), or 280 days.

Childbirth is classified into urgent, premature and late:

• Childbirth at 38-42 weeks is a normal period. Statistically, 70% of mothers give birth in the 39-41 week range. Primiparas often give birth 1 week later than the normal due date. But with repeated childbirth conversely, women are more likely to give birth before 39 weeks.
• Childbirth after 42 weeks is late. In this case, the child is considered to be post-term. There are about 9% of such births.
• Childbirth before 38 weeks is premature. The viability of the baby depends on the gestational age at delivery. The closer this period is to normal, the better.

Everything is individual, and in case of premature birth, a completely healthy and mature baby can be born, more often this happens over a period of more than 35 weeks. If the baby is underweight - less than 2500 grams, he will be considered premature.

The second degree of prematurity is established when the term of delivery is from 32 to 35 weeks and the weight of the child is less than 2000 grams. However, he also has a lot of chances to "mature" and gain weight after birth without the use of life support hardware.

With premature birth from 28 to 31 weeks, the child will be with grade 3 prematurity and low body weight (from 1000 to 1500 grams). Such children are successfully nursed in perinatal centers.

When a baby is born at a period of 22-28 weeks, he will have a 4th degree of prematurity. The baby has extremely low body weight and undeveloped lungs. There is no surfactant substance that ensures free breathing of the child.

Previously, the fruit was considered viable from 700 grams, now - with a mass of 500 grams or more. Such children are cared for in intensive care units using special transparent plastic boxes - incubators, which provide the necessary temperature, humidity and sterility of the environment. The baby is connected to a ventilator, feeding is carried out intravenously or through a tube, the necessary drug therapy is provided.

A baby born earlier than 22 weeks will not be viable due to severe immaturity. Currently, medicine is not able to leave such babies.

Causes of premature birth

The total share of all preterm births accounts for about 10% of cases. The cause may be maternal or fetal abnormalities, or a combination of various factors.

The most common ones are:

• Social and household - smoking, alcohol abuse, drug use, stress, extreme physical activity, malnutrition and hypovitaminosis.
• Pathology of the uterus - the consequences of abortions, other operations on the uterus, hypoplasia, endometritis, endometriosis.
• Pathology of ongoing pregnancy - placental abruption, lack of water, premature rupture of amniotic fluid, inflammation of the membranes, multiple pregnancies,.
• Diseases of the mother - diabetes, hypertension, rheumatism, bronchial asthma, severe anemia, mental disorders etc.
• Multiple anomalies in the development of a child, incompatible with life, at present, the latter is rarely the cause of premature birth, since women are trying to terminate pregnancy early for medical reasons.

In the presence of such risk factors, a woman should be especially careful, since she has a high risk of having a premature baby. She may have to spend some time saving.

Determining the expected due date is an important task. But in any case, the calculated period is approximate. It depends on many reasons. Therefore, with a long gestation period, a woman should listen to herself and expect childbirth, starting from the 37th week of pregnancy, or even earlier.

Helpful video on calculating due date