How is the pregnancy period calculated by week, from what day?

How to determine what stage of pregnancy? Every woman can approximately calculate when she became pregnant. Because this was most likely preceded by unprotected sexual intercourse. It is the moment of conception that a woman can take as the starting point for subsequent pregnancy . But usually it is very difficult to determine pregnancy too early. You need to wait a little more than a week from the day of conception. And starting from 3-4 weeks of pregnancy, a woman can already determine her new condition on her own. And after 3 weeks it’s not easy to even remember how this happened? All that remains is to find out how long the new life will last and when to expect the baby to be born.

What is it for

Our great-grandmothers also said that calculating the time of birth is a great sin. As God has ordained, so it will be. And for those who were impatient in this matter, the Lord sent difficult or premature births. It's good that these times are in the distant past.

Today, it is not difficult for a woman to calculate the exact date of pregnancy, and therefore the birth date. The period during which a woman is in an “interesting position” needs to be known for several reasons. And this is not always banal curiosity.

So:

• for a doctor to prescribe various studies;
• to calculate maternity leave.

And this is important for the mother herself in order to mentally prepare for an important event, to carry out her plans regarding the arrangement of the children's room, the acquisition of necessary things and equipment.

Of course, mommy knows the approximate gestational age, but it’s not easy to calculate an exact one that would be accurate to within a day without special knowledge or research.

With IVF and normal cycle

Interested in gestational age? How many weeks a girl is pregnant is not so difficult to find out. The main thing is to act consistently, and also decide on the appropriate diagnostic method.

More and more often, couples are undergoing IVF procedures. In this case, determining the day of pregnancy has its own characteristics. Women with a normal cycle, as a rule, can focus on the day when the last critical days began. The obstetric period will be counted from the corresponding day.

How does the doctor determine

Whenever a woman goes to the doctor to get registered with a gynecologist, one of the first questions she hears is the topic of her last period. The specialist is interested in the exact day they started. This is the pregnancy countdown.

It is quite easy to determine the date of ovulation and this method is one of the most reliable. Surely you know that the day of ovulation is the time of fertilization of the egg, and it occurs in the middle of the female cycle. This is the obstetric period of pregnancy. Girls who keep a monthly calendar know this date for sure.

But you can understand that fertilization of the egg has occurred by special signs:

• the lower abdomen is painful and painful;
• breasts swell;
• irritability appears.

In addition, there may be vaginal discharge. For an accurate result, questions about cycle length must be answered, which can be variable. And this complicates the task of independently calculating the due date. The factor of the duration of menstruation and its abundance is also important.

Be prepared to tell your doctor about all this. How can you easily determine a woman’s pregnancy at home? You can use Clearblue for this. This is a test whose design includes a digital indicator; it displays the period of the “interesting situation”.

True, he won’t tell you exactly to the day, but over the course of a week there will be no mistakes. Using the device is not difficult. You need to collect urine, preferably morning urine, and put the test in it. The display immediately displays the pregnancy period, if any, by week.

At the gynecologist

We found out how the pregnancy period is calculated by week. You can always find out more information about the fetus, as well as about the development of pregnancy, from a gynecologist. This specialist collects anamnesis and then provides the patient with the information she is interested in.

As a rule, at the first visit to the gynecologist due to pregnancy, the doctor asks:

• when was the last unprotected sexual intercourse;
• how long does menstruation last?
• when was your last period?
• Is there a delay in critical days?

Using this information, the doctor marks the beginning of pregnancy on a special gynecological calendar, and then determines its current duration and sets the PDR.

The woman will also have to undergo an examination in a gynecological chair. The gynecologist will be able to determine whether there is a pregnancy based on the condition of the girl’s internal organs. For example, along the cervix - it acquires a bluish tint.

Conception - the beginning of the beginning

Some women say that you can calculate the date of conception based on the last sexual intercourse that occurred at the expected time of ovulation. And from this day calculate the period. Yes, if your sex life has returned to normal and you make love with your husband no more than twice a week.

Ovulation is the time of conception; it occurs within 24 hours after the day the egg is released from the follicle. But sexual intercourse between spouses could have taken place three days earlier; sperm remain in the body for up to 7 days! Therefore, this method can misfire for a whole week.

The method of conception used by women expecting pregnancy is very practical. Every morning, a girl needs to measure her rectal temperature without getting out of bed. As soon as the temperature rises above 37 degrees, this means that the day of ovulation has arrived.

Important point!!!

Remember what I said about sperm viability? So, it is better to have sexual intercourse with your spouse a few days before ovulation than to be one day late with him. This will increase the girl's chances of getting pregnant. This method helps a woman calculate the exact duration of her pregnancy.

BT calendar

How many weeks is considered early pregnancy? This is usually how the first trimester of an interesting situation is described, up to 12 weeks (obstetric). Until this moment, every pregnant woman can, at her own request, have an abortion or register with the LCD in order to receive appropriate benefits in the future.

In any case, you first need to understand that conception was successful. This is not always easy to do, but if a woman is attentive to her body, she can try to achieve the necessary data as early as possible. A basal temperature chart helps judge the successful conception of a baby. True, it will have to be carried out in advance and over several months.

Usually, during ovulation, BT rises to 37-37.7 degrees, stays at these values ​​for several days, and then, if conception does not occur, drops to normal. In case of pregnancy, the temperature remains elevated in the early stages. This means that a deviation of the BT schedule from the norm is a clear sign of successful conception.

Now what? You need to look at the basal temperature chart and determine the date of conception of the baby. After this, all that remains is to calculate the difference between the day of pregnancy and the time when the girl decided to carry out the appropriate calculations.

Medical methods

The doctor can talk about the approximate duration of pregnancy already at the patient’s first visit. For him, it is enough to determine the size of the uterus in order to ascertain the embryonic stage of pregnancy. Moreover, the sooner a woman sees a doctor, the greater the likelihood of setting the exact time.

For example, at 5-6 weeks the uterus is the size of a chicken egg, and after three weeks it is the size of a goose egg. Many are confident that a more accurate diagnosis can be made using ultrasound. Actually this is not true. If you turn to ultrasound examination in the first weeks, the data will be more accurate.

But when a woman is prescribed a planned examination, that is, at 12-14 weeks, the specialist may already make a mistake. It's all about the individual development of the fetus, its size can be different, so determining what week a woman is at is often easier without an ultrasound.

One of the most interesting and reliable is the method of determination using hCG. It is by chorionic gonadotropin that a person is recognized about his “interesting situation.” Its level makes it possible to determine the age of the fetus, albeit approximately.

This parameter can be found out by donating blood and urine for analysis. How can a woman calculate how far into her pregnancy she is? You need to be guided by hCG standards.

How to determine the duration of pregnancy in the last trimester

Starting from the third trimester, it is no longer so important what the due date has come. Because all tests and procedures are performed on the already scheduled dates. Although the doctors generalized the timing of the first movements: this happens around 4-5 months. The date of the first noticeable movement (which should not be confused with bowel movements) must be entered into the mother’s exchange card. To independently find out the date of birth of the child. Women who have already given birth feel movements from 4 months. Therefore, they can add 5 months to the duration of their condition and calculate the birth. Primipara women can add 20 weeks to the date of the first movements and also find out the moment of the expected birth.

By measuring the uterus you can also determine how far along your pregnancy is. In the last weeks, the doctor measures the size of the uterus with a centimeter. The woman should lie horizontally with her legs extended. The size of the abdomen (uterus) from the diaphragm to the pubis, for example, is 36 cm, then the period is 36 weeks.

These are, perhaps, all the methods that most accurately determine the timing of pregnancy.

HCG norms

If a woman is carrying not one, but two babies, then the hCG level should be doubled.

IVF and long cycle

The situation with IVF is somewhat different if a woman has a long menstrual cycle. In this case, the obstetric period will differ from the embryonic period by about a month. Such a difference is unacceptable; it leads to serious problems in determining the PDR, as well as the current stage of pregnancy and fetal pathologies.

What to do if a woman has undergone IVF and has a long menstrual cycle? In this situation, as a rule, the development of gestation should be considered from the moment of embryo transfer. And in this case, gynecologists are not particularly interested in the beginning of the last critical days. In any case, such information will be superfluous for calculating the time of pregnancy development.

What difficulties might arise?

No matter how accurate the methods for calculating the timing of pregnancy are, they all only give an approximate date of birth. It is impossible to say with a 100% guarantee when the baby will be born.

According to statistics, 17% of pregnant women give birth on the day predicted by doctors, and the remaining majority give birth earlier or later. It turns out that even the most qualified specialists and high-tech equipment are not able to perform absolutely accurate calculations.

Labor is considered normal if it begins between 38 and 42 weeks of pregnancy. In these cases, the fetus is considered full-term. With some complications, labor begins prematurely. The cause may be pathology of the child’s development, stressful situations, various disorders in the mother’s body, and hereditary factors. All this must be taken into account when calculating the gestational age.

Postmaturity of a child is often observed with late gestosis, breech presentation of the fetus, in the case of taking hormonal drugs, and with impaired ovarian function. The hereditary factor also influences: if there have been late births in the female line, then it is likely that they will recur.

The menstrual cycle and ovulation are physiological processes. The length of the cycle ranges from 24 to 35 days. Therefore, any calculations based on them will always have a certain amount of error.

Standard calculations are based on the assumption that pregnancy lasts 40 weeks, and this is only true for a 28-day cycle. The time of ovulation is also determined by static data: 14 days before the start of menstruation. In fact, this process can happen 3-4 days earlier or later.

You can calculate the gestational age in different ways. The most accurate determinations are by the date of conception (ovulation), by the last day of menstruation and by ultrasound data for up to 12 weeks. Other methods can be considered auxiliary; they allow a large degree of error and are not used in medical practice for this purpose.

Even the most accurate method can be off by 1-2 weeks, or even more. This is due to the fact that the duration of gestation ranges from 38 to 42 weeks (normal), the menstrual cycle - from 24 to 35 days, the onset of ovulation can also occur several days earlier or later than expected in standard calculations.

Author: Olga Khanova, doctor, especially for Mama66.ru

What are “obstetric weeks”?

As mentioned above, it is almost impossible to determine the exact date when conception occurred. Therefore, for the convenience and simplicity of calculating the gestational age, the concept of “obstetric weeks” was introduced. What is it? This is a calculation of the gestational age not from the day of ovulation, but from the first day of the beginning of the last menstruation. That is, these indicators will differ from the true period by 2 weeks. So, if a period of 38 weeks was indicated, then, according to obstetrics, it is 40 weeks. This is exactly how the deadline is set in the antenatal clinic, and the PDR is also determined.

conclusions

The expected date of birth, which can be calculated in several ways, will give the girl an accurate idea of ​​how long she will have to wait for her little “miracle.” You can use any of the above methods or try them all. Usually, deviations between them are no more than 1-2 days. We recommend using our calculator and calculating your due date by period (or by conception) online. In this case, in addition to the expected date of birth, in addition, the expectant mother will receive a unique guide to action and tools for monitoring the development of her baby week by week.

Trying to calculate the due date by week

Some women mistakenly add 9 months and get a “supposed” secret date. This is incorrect, because. pregnancy lasts a little longer - approximately 280 days or 40 weeks.

True, the doctor quickly eliminates this error and helps the patient decide using 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 date birth, which your gynecologist will add to the card.

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

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

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

You can use our Due Date Calculator