The average human pregnancy lasts. Factors influencing length of gestation? Components of natural processes

It is generally accepted that the number of days from conception to birth is 280, but this is only a conditional number of days of bearing a child, which is calculated from the first day of the last menstruation. In fact, the average length of pregnancy to delivery from the day of conception is 267 days. A baby born between 253 and 281 days of pregnancy is considered full-term. Therefore, a child born a week or a week and a half ahead of schedule, in this case, the expected date of birth (DAD) cannot be considered premature, and also children who delay birth for the same period are not post-term.

Each pregnancy is individual, and children themselves decide when to be born in view of their maturity - this is what nature provided. After all, a woman can never say with certainty the exact day of conception, since the survival rate of sperm is ten days, which means that fertilization can occur a week after unprotected intercourse.

Methods for counting days until childbirth from the day of conception

The average pregnancy lasts 38 weeks, but this does not mean that at exactly 38 weeks, birth is considered normal between 37-41 weeks of pregnancy.

There are different methods for determining the gestational age and expected date of birth:

• From the first day of the last menstruation
• According to ultrasound examination
• (the most inaccurate and absurd, since every woman can feel the baby moving at different times, it depends on many factors, one of them is the severity of the fat layer on the abdominal wall)

To find out how many days before birth from conception, it is difficult to determine the exact date of conception or ovulation, so gynecologists calculate the date of birth from the last menstruation, since almost all women remember this date. It’s a paradox, because a real pregnancy cannot occur in , so the pregnancy period calculated in this way is usually called menstrual or gestational, but in fact, conception occurred approximately two weeks later, that is, at the moment of ovulation, this period is called ovulation or fertilization.

As a rule, ovulation occurs fourteen days after the end of menstruation, so if you calculate how many days from conception to birth you need to subtract fourteen days from the average length of pregnancy, that is, 280 minus 14, you get 266 days. But again, everything is individual and in some cases ovulation may occur a little earlier or later. Therefore, gynecologists came to the conclusion that pregnancy is considered normal to last 266-294 days, that is, the conditional number of days of pregnancy plus or minus fourteen days.

Good day, blog readers.

Have you ever noticed such a situation - a pregnant woman registers, a gynecologist determines the date of birth. But the date often does not coincide with the actual gestational age?

It happens that the baby is in no hurry to be born. And if in one case this is not scary, then in another it has negative consequences. I wonder how long pregnant women actually walk? What happens to them? Let's trace the whole chain of events.

A real miracle of nature happens under the hearts of women. Thanks to modern technology, you can now find many videos of step-by-step intrauterine development. But seeing and feeling are completely different things.

I trimester (first 12 weeks). The baby begins to develop.

As soon as the sperm reaches the mature egg and penetrates it, after 26-31 hours the zygote (fertilized cell) begins to divide and an embryo is formed.

After a day, the little miracle consists of 4 cells, and after another 2 days - of 8, after 4 days from conception - from 10 to 20 cells, on the 5th day the number of cells increases to several dozen.

It is noteworthy that the embryo does not grow. How are the cells placed? With each new fragmentation they decrease in size. After giving birth, I can’t even believe that at the beginning of the journey it was only 0.14 mm (on the 4th day).

Until the thirteenth week of pregnancy, the baby is especially vulnerable because the placenta has not yet fully formed.

It is very important that the mother does not take strong medications, is healthy and protects herself from diseases especially carefully, is not near harmful substances or industries, etc.

The main function of the placenta is to protect the baby from dangers from the external environment and to establish the exchange of useful substances with the mother’s body, therefore from 1 to 12 weeks, the unborn child is practically defenseless against threats.

After the first week, the embryo reaches the uterus and is securely attached to its walls. It is at this time that a conventional test can determine pregnancy.

If before the fourth week of the interesting position, the cells of the embryo only increased their number, now the specialization of tissues begins. Then the future baby develops very dynamically:

Week 5. The size of the baby is already 4 mm. The head has formed, which makes up the main part of the embryo, the body becomes curved, but the limbs are still missing.

The blood flow system, endocrine system, digestive system, respiratory system, and kidneys begin to form. The small, still two-chambered heart is already working, albeit at half capacity. The body is covered with skin.

Week 6. The placenta begins to form and develop in the wall of the uterus.

Week 7. The heart acquires the correct structure—four chambers—and blood flow improves.

Week 8. All organs of the future person are already working.

Week 9. Embryonic development is completed and the embryo becomes a fetus. During the formation of the brain, cell differentiation occurs.

At this stage, the placenta continues to form: a dense network of vessels has increased significantly and is developing, but it cannot yet fully perform its functions.

Week 12. The fruit weighs about 20 grams and reaches 9 cm in length. The skeleton continues to form, there are already ossification points.

All the baby’s organs are formed and functioning. The blood, urinary and digestive systems work well, and the genitals appear.

The head makes up almost half of the entire body, and the face takes on natural shapes: eyes covered with eyelids; mouth and lips, nose, ears.

II trimester (13-24 weeks): we continue to grow

From the beginning of the 2nd trimester, the placenta begins to perform its functions in full. The fetus is more protected from harmful environmental influences. The future baby has grown to 10 cm, and weighs from 25 g.

The baby is growing rapidly and now his weight can be up to 650 g, and subcutaneous fat appears. Height up to 32 cm. All organs of the baby are already formed and if he is born, then has every chance to survive.

Such children need urgent specialized help and special conditions. Until the baby grows up and gains the required weight, he will be kept in an incubator - a special incubator for premature babies with a constant temperature and sterility.

III trimester (25 - 40 weeks): getting ready to meet your mother

In the third trimester, the baby mostly gains weight. All body systems mature for independent functioning.

At 32 weeks, wrinkles on the skin disappear, it has its usual appearance, but remains red. Therefore, if the baby decides to be born at this time, he will have to spend some time in the incubator and undergo certain therapy.

Babies cannot breastfeed yet; they have to be fed with a tube.

The peculiarity of the 36th week is that the little man becomes more and more like a toddler who will be shown to his parents in the delivery room.

It becomes rounder, some grow long hairs, and the cartilage on the ears becomes denser. Usually, when babies “come out into the world” at this stage, they can successfully adapt to the external environment and successfully undergo childbirth; their height can reach 46 cm and weight – 2.5 kg.

They don't need special equipment. The child has a sucking reflex and can scream loudly. Such babies may experience postpartum weight loss due to slow metabolism.

Pregnancy without abnormalities lasts an average of 40 weeks. At this stage the fruit is considered mature. Its height can be from 47 centimeters or more, and its weight can be from 2.5 kg. He is ready for childbirth, and after meeting the new world, he screams loudly, actively moves his limbs, opens his eyes, and sucks well at the breast.

If the baby is “delayed”

The consequences of premature birth described above are due to the immaturity of the child’s body, and this is understandable. What if the baby is in no hurry to meet his mother? Is it good or bad?

Usually mothers are more afraid when the baby arrives earlier, and the extra weeks of pregnancy are ignored. But if nature intended that a woman carries a child for 40 weeks, then a deviation even in the direction of increase can also have consequences.

If the pregnancy lasts 10-14 days longer than 40 weeks, then doctors believe that the expectant mother is overbearing. There are:

Prolonged pregnancy , which lasts longer than a certain period by 10-14 days and ends in natural birth.

The baby is born without signs of post-term pregnancy. The reason may be the difference between the calculated period based on the first day of the last menstruation (this is how the date of birth is usually determined) and the actual day of conception.

You can more reliably determine the timing of your baby’s birth by the day of ovulation.

True post-maturity is a pathology and has its consequences. The baby is born with obvious signs of a longer stay in the womb:

• aging placenta
• no original lubricant
• wrinkled dry skin
• a small volume of amniotic fluid; the water may also be grayish or greenish in color.

Since the placenta and umbilical cord have already fulfilled their function, and a mature baby requires more oxygen, there is a risk of developing hypoxia.

If the baby was not born on time, then the meconium passes directly into the amniotic fluid. The bones also begin to harden, which is fraught with injury for both mother and child during childbirth.

The permissible duration of pregnancy in such cases is determined by doctors, based on monitoring the condition of the child and mother.

If labor still does not occur, a decision is made about stimulation.

How to determine the timing correctly?

Your gynecologist can determine the duration of pregnancy in the early stages of 2-3 weeks. At this stage, the doctor will be able, exactly to the day, to say “how much baby” based on the size of the uterus.

And after 8-12 weeks, the size of the uterus depends on the individual characteristics of each woman, and it is more difficult to determine the timing.

Can be determined using ultrasound at 8-12 weeks. Later, it is difficult to determine the timing in this way, since each fetus develops differently, and in the 2-3 trimester it is not necessary to take into account the results of the study.

The expectant mother herself can quite accurately determine the gestational age based on the day of ovulation. If the female cycle consists of 28 days, then the 14th day is considered the day of ovulation, and if it is 35 days, then on the 17th - 18th day. Thus, the day of conception should be considered the day of ovulation.

Another way to find out the exact gestational age is to pay attention to the day the baby first moves. When a woman is about to give birth for the first time, she will feel the baby moving at 12 weeks, and if in the second (third), then at the eighteenth week.

A lot of films and short videos have been made, written in books and on the Internet, and it seems that it is no longer possible to add anything...

But mothers and those who are just planning to become one are sure that not a single book can convey that happiness - to feel like one with the baby.)))

See you again!

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P/S: There is a bonus for the article. And such a guide to an interesting situation will definitely not be superfluous for you - Guide for pregnant women, compiled by an experienced obstetrician-gynecologist with impressive work experience.

04/25/2017 / Category: / Mari no comments

Every woman learns about pregnancy differently. Some people wait a long time for two lines on the test, while others accidentally find out about this during their next visit to the doctor. In any case, this news changes a lot in our understanding of the surrounding reality. Many questions immediately arise in your head, and one of the main thoughts is when is the baby due? On what day exactly will this wonderful event happen? How to correctly calculate the expected date of birth?

How many weeks does pregnancy last in women?

Despite the apparent simplicity of the question, there may be several answers to it, although the preliminary date of birth will be the same. How is it that the period in weeks is different, but the due date is the same? Let's try to figure it out.

Typically, from the moment of conception, pregnancy lasts 38 weeks. To be more precise - 266 days. As a rule, few people can say exactly on what day ovulation occurred and conception occurred. But almost everyone knows the date of the last menstruation, fortunately now every girl has an application on her phone, where an accurate count of all female physiological processes is kept. Therefore, this date is taken as the starting point.

It is known that ovulation occurs approximately 2 weeks after the start of menstruation. And to determine the gestational age based on a known date, just 2 weeks are added to this period of 38 weeks. Therefore, it is generally accepted that a normal pregnancy lasts 40 weeks or 280 days. And it is these 40 weeks that are counted from the date of the start of the last menstruation to calculate the date of birth! Let's divide 280 by 30 and get about 9 months, which everyone knows about.

You and I all understand that in the first 2 weeks, which is precisely the interval between menstruation and ovulation, there is no pregnancy yet. Therefore, weeks calculated in this way are called obstetric weeks. And the period of real pregnancy from the moment of conception in normal weeks is always 14 days less, exactly those 266 days that we talked about earlier.

But that's not all! 9 months – that’s how ordinary people, not doctors, are used to thinking. And in obstetrics and gynecology it is customary to say that pregnancy lasts 10 so-called lunar months. Why? It's simple. The duration of a girl's normal cycle is 28 days. Divide 280 by 28 days and get 10 months.

Your head is spinning, isn't it? But there is no need to panic. Everything was invented long ago before us. In order to find out the expected date of birth, you just need to use a calculator, of which there are a huge number on the Internet. You can enter into it either the date of the start of your last menstruation, or the date of expected ovulation, and you will receive the date of birth - in other words, PDR. And the weeks will be counted in your antenatal clinic.

Is the traffic date correct?

Why do movies so often show how the onset of labor takes a woman by surprise, and how someone gives birth without ever reaching the hospital? After all, if you know the exact date, you can prepare in advance? All this is true.

But, firstly, no one can say for sure on what day ovulation occurred, when the egg was fertilized, so calculations of the exact gestational age are very arbitrary. Secondly, the duration of pregnancy depends on many factors: the health of the mother, her mental state, heredity, the development of the baby, and so on. Therefore, it is generally accepted that a normal pregnancy lasts from 38 to 42 weeks: plus or minus 2 weeks from 40.

As you can see, the difference in amount is about a month. There is nothing to worry about if you listen to your own condition, attend the antenatal clinic on time, and undergo all the necessary examinations. This means that doctors are constantly monitoring your condition, and you will be ready for labor whenever it begins.

Does gestational age depend on the sex of the child?

It is believed that pregnancy with a girl is shorter than pregnancy with a boy. And that mothers of boys usually go beyond the period of PPD by at least 1 week. But there is no scientific confirmation of these popular beliefs (and they cannot be called differently): according to statistics, the number of boys born at 38 weeks is equal to the number of girls born at 42 weeks.

There is also no scientific confirmation of the talk that the first pregnancy lasts longer than the second or third. Perhaps each subsequent birth is easier than the previous one, but exactly how long each pregnancy will last does not depend in any way on the number of children the woman has. Therefore, try not to get hung up on what gender of child you are expecting or what type of pregnancy this is. This is not so important; it is better for your baby to know when to be born.

IMPORTANT! The length of pregnancy does not depend on the gender of the child or the number of children already born. Everything depends only on the body of the expectant mother. The most important thing that she can and should do is to lead a healthy lifestyle, eat well, be less nervous, worry less and get as many positive emotions as possible. And then the baby will develop correctly, be born on time and healthy!

Have a good pregnancy and an easy birth!

An experienced gynecologist can determine the approximate gestational age during a pregnant woman’s first visit to him even before she is registered. But when she comes home, the newly minted expectant mother will make her own calculations about when conception could have taken place, and will be perplexed: most likely, her calculations will differ from the doctor’s estimates by an average of two weeks.

This is what confuses most women: when they become pregnant for the first time, they try to understand how to correctly calculate the due date and how many weeks a pregnancy normally lasts.

Let us say right away that this period may be different for everyone, provided that the fetus develops normally and the entire pregnancy proceeds safely. But based on centuries of practice, obstetricians came to the conclusion that the average duration of this period is 280 days. In terms of weeks, this will be 40, but we are talking about the obstetric period. What does it mean?

Most of us probably know that the highest probability of conception exists during the period of ovulation. Moreover, this is a prerequisite for pregnancy: the egg must mature and leave the follicle so that the sperm can fertilize it. Finding out the exact date of ovulation is not very easy, although it is possible if special examinations are carried out during this period. But most women do not carry them out, and even if it is known exactly when ovulation occurred, it is completely impossible to record the moment of conception: this can happen immediately after ovulation, or a day or two later. In addition, in each individual case, it takes different times for the fertilized egg to move to the uterus and implantation into its cavity, and therefore it is impossible to determine when pregnancy begins to develop, that is, when the egg takes root.

As you can see, there can be a lot of nuances, and all of them ultimately affect the duration of a woman’s pregnancy. Among the most significant factors, doctors name the following:

• timing of ovulation (duration of the menstrual cycle);
• timing and duration of implantation;
• the age and health status of both representatives of the pregnant couple;
• sperm viability and activity;
• features of intrauterine development of the fetus;
• hereditary factors (if a woman’s closest relatives gave birth prematurely or were overbearing, then there is a high probability that in this case the pregnancy will also last less or longer than average);
• psychological factors (in some cases, a woman is even able to “program” herself to give birth on a certain day).

But let's get back to obstetric calculations. Since determining the exact date of ovulation is difficult, doctors calculate the duration of pregnancy based on the date of the last menstruation - almost all women remember it. This period is the starting point when determining the period by the gynecologist. But in fact, conception can take place only 13-14 days after this, which is why there are discrepancies in the calculations of doctors and in the personal calculations of pregnant women.

In view of the fact that a 28-day menstrual cycle is considered to be a guideline, and ovulation most often occurs 13-15 days after its onset or approximately two weeks before the start of the next menstruation, and it is during this period that conception can occur, it becomes clear why there is such confusion.

So, gynecologists consider the beginning of pregnancy to be the date when the last menstruation began (although there was no pregnancy at that time, of course), and this period is called obstetric. If the beginning is counted from the date of conception of the baby, then this period is called embryonic.

We have already said that a normal pregnancy lasts 40 obstetric weeks, or 10 obstetric months. According to the calendar, this period is just over 9 months, and this is exactly the duration of intrauterine life that babies call in everyday life. If we start from the day of conception, then the duration of gestation is 38 weeks (or approximately 266 days), because ovulation and conception occurred after menstruation, which doctors consider the beginning of this pregnancy.

Since obstetric calculation cannot be guaranteed to be highly accurate, the actual gestational age may differ slightly. For this reason, a normal-term pregnancy is considered to be one that ends in natural birth at a period of 37 to 42 obstetric weeks.

So, to summarize: normally, 38 weeks or 266 days pass from the moment of conception to birth, and 40 weeks or 280 days from the date of the last menstruation to childbirth.

How many weeks does the second and third pregnancy last?

There is an opinion that the second birth occurs earlier than the first. That is, the second child is more likely to be born prematurely, but this is not entirely true.

Firstly, each baby develops in a completely different way, just as each woman carries a baby in a completely different way. Most often, it happens that different pregnancies and births for the same woman are very different from each other. But the timing may be the same. Women on forums very often discuss this issue, and many of them confirm from personal experience: there is no connection between the number of pregnancies and its duration! Some gave birth to all their children at the same time, others at different times, but it happens with equal frequency that the second child is born either earlier or later than the first.

Secondly, there is still a certain tendency that the second birth may begin earlier than the first, obstetricians say. But on one condition: that the woman conceived children one after another. If several years have passed between births, then the woman’s body “perceives” the repeated conception as having happened for the first time.

How many weeks does pregnancy last with a girl, with a boy, with twins?

But the opinion that boys are born before girls (and according to some versions, just the opposite) is a pure myth that has no basis. The gender of the child does not in any way affect the duration of gestation. Such factors may include heredity, the emotional and mental state of the woman, but to the greatest extent it depends on the health of the mother and the presence/absence of complications of this pregnancy.

No matter how long the pregnancy lasts in your case, the main thing is that the baby is desired and loved! And regular visits to the antenatal clinic will help reduce all possible risks to a minimum. After all, this is why the period is determined in weeks, so that the doctor can analyze the compliance of the child’s development with the standards established for a particular period.

Especially for - Ekaterina Vlasenko

How long does pregnancy last for women? Unfortunately, it is impossible to know the date of birth with absolute certainty. The date given by doctors is EDA - estimated date of birth.

There are cases when the actual date of birth coincides with the expected one. But all these cases are nothing more than mere coincidences.

Even if the woman knows exactly the day of conception and the date of ovulation, it is impossible to determine the speed of the sperm, how many days the egg travels through the fallopian tubes, when it is precisely implanted, how long it takes for the fetus to fully mature and when the child is ready to be born.

Because everything Our bodies are individual, so in each case these processes proceed differently. Doctors use the average statistical standard, which is usually oriented towards.

So how many weeks does a woman’s normal pregnancy last? Scientists have calculated that in 80% of cases from the moment of fertilization to the onset of labor passes 266 days, respectively, this equals 38 weeks.

But the difficulty in this calculation is that, as a rule, expectant mothers do not know the exact day of conception.

The date of the last menstruation is remembered more accurately, so this date is taken as the basis for the calculation. Thus, it turns out that 40 weeks pass from the day of the start of menstruation to the birth. Therefore, to the question: how many weeks does pregnancy last, obstetricians answer - 40 weeks (280 days).

However, on the first day of the onset of menstruation there was no real pregnancy yet, so the period calculated in this way is approximate. It is called menstrual or gestational age.

In fact, the fetus is about two weeks younger. This term is more accurate. It is called ovulation or fertilization. To more accurately determine the date of their birth, expectant mothers should calculate the date of their ovulation.

How to calculate the date of ovulation?

It's very hard to believe, but there is only one day in every month, when is it possible to get pregnant. In very rare cases, this day occurs twice during the month.

There is a simple formula that can be used without any auxiliary devices. Scientists have found that Absolutely every woman ovulates 14 days before the start of her period.

If the menstrual cycle lasts 28 days, then it turns out that ovulation will occur on the 14th day after the last day of ovulation.

Agree, this calculation is very simple. However, there is one catch - this method is suitable only for those women who have a regular cycle. In addition, you can only calculate the day of ovulation if you have an accurate cycle schedule for at least six months.

Moreover, in individual cases, ovulation may occur a little earlier or a little later. But, if we take the expected date as the starting point, then it turns out that the pregnancy actually lasts 266 days (280-14=266).

That is why doctors call a pregnancy that lasts from 266 to 294 days or from 38 to 42 weeks a normal full-term pregnancy.

When calculating, it is easy to notice that 280 days (40 weeks) are precisely 9 months.

However, obstetricians have their own month count. According to their calculations pregnancy lasts 10 months. The fact is that the so-called lunar months, which consist of 28 days, are taken into account. This is exactly the period the cycle lasts for most women.

Factors influencing the length of pregnancy

First of all, the duration of gestation is influenced by the health status of the expectant mother and other factors. For example:

• heredity;
• psychological condition;
• fetal development;
• intrauterine condition.

In case of prematurity, as well as the due date, there are additional threats of adverse birth which may affect the health of the fetus and mother.

These phenomena may be caused by neuroendocrine disorders, previous diseases and previous abortions. According to statistics, women who have been treated for pregnancy are more likely to carry their fetus to term. A post-term pregnancy is considered to be one whose term has crossed the line 42 weeks.

Pregnancy too long

Causes

Many expectant mothers are more afraid of a premature pregnancy than a post-term pregnancy. However, in fact, post-term pregnancy is very dangerous.

Doctors still cannot give an exact answer as to what is the reason for pregnancy being too long. It is customary to highlight two factors of post-maturity - medical and psychological.

From a medical point of view, the cause of the problem lies in the woman’s physical unpreparedness for childbirth.

This can be explained the following factors:

• late cervical ripening;
• muscular disorders of the uterus and myometrium;
• slow fetal development;
• hormonal problems;
• endocrine and gynecological diseases of women;
• pathology of the uterus;
• heredity.

Moreover, The length of pregnancy also depends on the age of the mother. Most often overstayed during the first late pregnancy.

All reasons that can be attributed to the medical aspect are identified through additional examinations. But the psychological side is quite difficult to identify.

It happens that psychologically the woman is not at all ready for childbirth. The reason for this is an unconscious fear of the birth process. A woman may fear pain or the possibility of losing the baby, slowing down the onset of the natural process.

At the first signs of post-maturity, you should consult a doctor. By performing an additional ultrasound, the specialist will be able to determine the condition of the placenta, amniotic fluid and, of course, the child.

When, after undergoing an ultrasound, traces of meconium are found in the amniotic fluid or problems with the baby’s heartbeat are detected, then, in this case, the doctor will definitely prescribe induction of labor or.

These appointments should never be refused, because the consequences of a post-term pregnancy can be disastrous.

Consequences

In 40% of cases, during late labor occurs placental dysfunction. Thus, she is not able to provide the child with the necessary amount of nutrients and oxygen.

Often In post-term pregnancy, the fetus gains excess weight, which naturally complicates the birth process.

Also, in 20% of post-term babies there is a so-called "overmaturity syndrome", in which the skin changes.

There is too little subcutaneous fat in the child’s body, which stunts his growth. In addition, births that begin after 42 weeks have a higher incidence of birth injuries.

Most often this is expressed in Erb's palsy, fractures of the limbs and collarbones, as well as hip dysplasia.

In this case, the woman in labor is also exposed to additional risk, which consists in the next moments:

• high probability;
• risk of uterine damage;
• prolonged labor;
• occurrence in the postpartum period.

No wonder this condition is called pathology of pregnancy. Therefore, to avoid such unpleasant consequences, you should consult a doctor.

However, we must not forget about the conventions of calculating the duration of pregnancy. As was said before, plus and minus are allowed for a duration of two weeks. There is no need to worry in vain until 42 weeks.

It is much more useful in the last days of pregnancy to prepare yourself psychologically and physically for childbirth.. During this period, expectant mothers need better quality rest.

Childbirth is a difficult process for any woman’s body, so it’s worth dedicating enough time to sleep. Many women attend specialized courses where experts tell them how to survive childbirth better and safer.

Moreover, now on the Internet you can find a lot of supporting information that will make a woman more confident and eliminate unnecessary fear.

The main thing to remember is that after giving birth, there will be a meeting with your most beloved and closest person!