Find out the exact duration of pregnancy by week. Methods for determining due date in the early stages of pregnancy

As soon as a woman becomes pregnant, she is immediately interested in the question: how to independently determine the duration of pregnancy at home? Indeed, with the help of such calculations one can calculate approximate date the birth of your child. In addition, the expectant mother may not know the exact day of conception.

Some try to calculate the onset of pregnancy based on the timing of ovulation, but you should know that ovulation occurs between the 8th and 16th day of the cycle. Therefore, fertilization can occur between the 8th and 18th days menstrual cycle, taking into account the viability of sperm in the female genital tract. After all, it is in this case that conception most often occurs. In addition, the duration of pregnancy may not be 40 weeks, since normal pregnancy is full-term by 37-38 weeks, so after this period, labor can begin at any time.

A pregnant woman may also have more than one fetus, so childbirth can occur 2-3 weeks earlier than with one fetal pregnancy. Also, any individual characteristics of a woman can affect childbirth, these could be diseases, for example, diabetes, hypertension or other diseases. But, despite this, it is still possible to determine the approximate gestational age at home.

Determination of gestational age, relative to ovulation and date of conception

Determine correctly exact date pregnancy, you can use a calendar. As you know, ovulation is the period of the menstrual cycle in which the conception of a child occurs. And during ovulation from the female ovary to fallopian tube an already mature egg comes out and is met by a sperm. As a result, pregnancy occurs. The date of ovulation is used to determine the duration of pregnancy. There are small tips on how to recognize the symptoms of pregnancy in a woman.

A woman ovulates approximately in the middle of the menstrual cycle. And if a woman’s cycle is about 28 days, then ovulation will occur around day 14. And when a woman’s menstrual cycle is 35 days, ovulation will occur on the 17-18th day of the menstrual cycle. Therefore, the exact period of pregnancy should be counted from the day of ovulation. Moreover, knowing the day of ovulation, you can plan your pregnancy and know the month and approximate date when the baby is born.

It is worth noting that you can easily determine your ovulation yourself at home using ovulation tests that are sold in pharmacies, or you can determine it by measuring your basal temperature. To do this, you will need to cleanse the intestines at home using an enema, and then measure the temperature in the rectum with a thermometer. Peculiarities:

1. The entire first half of the menstrual cycle basal body temperature stays at 37 degrees.
2. The day before ovulation it decreases slightly.
3. On the day of ovulation and all subsequent days, the temperature will rise and will be 37-37.2 degrees.

Therefore, how to accurately determine how far I am in pregnancy by the date of ovulation can be done using a regular thermometer.

However, there are also women who know how to determine the duration of pregnancy, focusing on their subjective feelings. And these sensations include pain in the lower abdomen, an increase in the amount of vaginal discharge, or an increase in libido. In addition, in some cases, a woman may experience no pain during menstruation, which indicates some positive changes.

Therefore, it is not difficult for such sensitive women to determine the time when conception occurred. But still the most exact way Ultrasound is used to determine the duration of pregnancy. In addition, with the help of this study you can find out the date of ovulation. However, constant trips to the ultrasound room will require a lot of money, so you can try more affordable methods for calculating the gestational age.

Determination of gestational age relative to the date of the last menstrual period

This is perhaps the simplest and known way determination of pregnancy juices and it is called the Naegele method. However, this method helps to calculate the due date rather than the pregnancy. According to this method, to determine the timing of birth, it will take from the first day last menstrual period you should subtract three months, and then add seven days to the number. And in accordance with the obtained date of birth, you can easily calculate the duration of your pregnancy.

Determination of pregnancy due to an experienced gynecological examination

Without a doubt, if a woman came for an examination to a gynecologist in the very first weeks of pregnancy, for example 3-4 weeks, then it will not be difficult for him to determine the duration of pregnancy. And in this case, the specialist determines the gestational age based on the size of the uterus.

It will not be difficult even in a period when a woman has just recently taken a pregnancy test and immediately came to the gynecologist.

For example, at 4 weeks its size can be compared chicken egg, and at 8 weeks the size of the uterus can be compared to a goose egg. And if this is a very experienced gynecologist, then the obstetric examination will be professional; as a result, he can determine the duration of pregnancy using a vaginal examination and set the date with an accuracy of one day.

After a period of 8-12 weeks, it is very difficult for a gynecologist to determine the size of the uterus, since each woman’s uterus and its size may differ. Therefore, the gynecologist can not only determine a more accurate period, but also provide full instructions on what is possible for pregnant women. For example, is swimming beneficial for pregnant women or not, or what exercises or exercises should be done to correct posture and strengthen muscle tone. During this period experienced doctor you can determine the gender of the unborn child or several at once.
Determining the gestational age using the result of a modern ultrasound examination can more likely determine the exact period if the ultrasound is performed in the early stages, this is 8-12 weeks. For more long term Each child develops differently, so it will be difficult to determine an exact date. And if the fetus gains insufficient weight after 20 weeks of pregnancy, then at this examination a diagnosis of poor fetal development is made.

Typically this diagnosis is given to women of fragile build. And on the one hand, this is wrong, because a full-term baby can weigh 2.8 kg or 4 kg. Therefore, the weight and size of each child may vary significantly. For this reason, it is not necessary to pay attention to the period indicated on ultrasound in the 2-3 trimester of pregnancy.

Useful materials:

For correct management pregnancy, the gynecologist needs to know the woman’s gestational age. Based on these data, the expectant mother will be prescribed necessary tests, Ultrasound and examinations.

It is also important for a woman to know the due date in order to prepare mentally for childbirth. Based on the duration of pregnancy, you can accurately calculate the time of care in maternity leave and preliminary date of birth (PDD).

Methods for determining gestational age:

1. Obstetric method

Upon first admission to antenatal clinic The gynecologist will ask about the date of the last menstruation, the duration of the menstrual cycle and its regularity. This data will be needed to determine the gestational age based on menstruation.

Due to the irregularity of the cycle and its duration, the date of conception for most women is difficult to determine. If a woman’s cycle is regular and lasts 28 days, then ovulation and conception will occur on the 14th day after her period.

IN obstetric practice use Naegele's formula: subtract 3 months from the first day of the last menstruation and add 7 days.

We add 7 days - it turns out July 15, PDR. If a woman’s cycle is 21-35 days, then the maximum period will be plus or minus 6 days.

This method of determining pregnancy is called obstetric.

2. Embryonic method

The embryonic gestational age is calculated from the date of conception, which coincides with the date of ovulation. Conception occurs during ovulation after the egg leaves the follicle within one day. In the female genital tract, sperm can survive for about 3 days. Therefore, the date of conception may differ from the date of sexual intercourse.

Women with a regular menstrual cycle can accurately determine the period by the date of conception.

The embryonic period may differ from obstetric period on average for two weeks.

3. Gestational age according to ultrasound

You can determine the exact gestational age by ultrasound up to 12 weeks by the average internal diameter of the egg and changes in the amniotic sac.

The size of the fetus according to ultrasound coincides with the obstetric period and has an error of one week.

Ultrasound examination helps to learn about the formation and development of the child. If according to ultrasound the term is less than the obstetric period, this does not mean that it is incorrectly determined.

The following reasons may hinder the proper formation of the fetus:

• improper functioning of the placenta;
• multiple pregnancy;
• diseases of the expectant mother;
• malnutrition;
• bad habits;
• chromosomal abnormalities in a child.

If the ultrasound term, on the contrary, is longer than the obstetric term, then this may indicate a large weight of the unborn baby.

The reasons for a child's high weight may be:

1. Hereditary factors;
2. Poor nutrition during pregnancy;
3. Diabetes.

If an ultrasound examination is performed later than 12 weeks, there may be a discrepancy with the child’s developmental norms.

Determining the gestational age must be carried out in total: know the date of onset of the last menstruation, perform an ultrasound, know the date of conception and examine the formation of the fetus.

Pregnancy calculators

The calculator calculates the duration of your pregnancy based on your last menstrual period. The gestational age is obtained in “obstetric” weeks.

As a rule, each pregnant woman has her own calendar, where she enters all the necessary data, circles important dates, takes notes. It is usually used to calculate the gestational age.

Considering the nine-month duration of this period, calculations on paper seem to be a very routine task. But modern women live in great time- they are not at all obliged to keep such a calendar and engage in tedious arithmetic, unless, of course, they are so sentimental that they decided to keep their weekly notes as a memory of wonderful time gestation. You can safely entrust the worries about calculating your pregnancy period to the program. After all, for those who prefer to spend their free hours on activities that are much more useful for the future baby and his mother, there are numerous virtual services like this (we hint at our calculator).

What is needed to calculate the gestational age?

In order to calculate the gestational age right now, you only need to remember the date when your last period began and enter it in the appropriate fields of the form. This number is the starting point of your pregnancy. We are talking about the so-called “obstetric weeks” - all over the world it is customary to count pregnancy this way, although fertilization occurs only in the middle of the cycle. This measure is necessary for the convenience of doctors, but often causes surprise and misunderstanding among patients.

It is worth noting - when ultrasound examination of the fetus, you will be faced with the fact that the gestational age known to you can be calculated differently - by the weeks of the fetus’s life, that is, from the day of conception. You may even find a note on the ultrasound examination results sheet that will indicate both dates. In order not to be embarrassed by such contradictions, feel free to check with your doctors about what exact period pregnancy is underway speech, real or obstetric?

It is very important to emphasize that even if you know exactly the date of conception of the baby, in order to calculate the gestational age using a calculator, you need to use the date of the start of the last menstruation. If you find it difficult to remember, count back 2 weeks - with a standard 28-day cycle, ovulation most often occurs on the 14th day.

I don't remember when I had my period. What to do?

Sometimes it happens that a woman does not know when she had her last period, for example, she does not remember, does not monitor the regularity of her cycle, or has just stopped taking contraceptives. If you have no idea what your gestational age is, they can calculate it using. The most reliable data is obtained in the early stages (up to 12 weeks), when the rate of development of the fertilized egg is still very high and changes are noticeable literally every day. The size of the fertilized egg alone, without taking into account the proportions of the fetus, will tell the doctor a lot. For more later There may be errors of up to 2 weeks.

Another very informative method that allows you to calculate the gestational age is biochemical - a woman’s blood test for hCG content - chorionic gonadotropin person. This hormone is produced by the fertilized egg and is present in the body only during pregnancy (by the way, the well-known instant pregnancy test is based on its determination in urine). Contents and healthy pregnancy clearly corresponds to deadlines. It is worth noting that this is far from a routine method, which requires a lot of time and money, and is used mainly for medical reasons.

It should be mentioned that finding out the gestational age, calculating and guessing the probable age of the fetus is within the competence of the obstetrician when conducting a vaginal examination in the early stages. The main object of study in this case will be the uterus and palpation (manual) determination of its size. Of course, we are not talking about absolute accuracy, but the data obtained is quite sufficient for successful health monitoring expectant mother and fetus.

Questions for the article

On ultrasound on June 30, 2017, the doctor said nothing was visible, just a cyst...

I looked at the test, but I had negative result. but so...

The lower abdomen hurts periodically, it swells, it hurts, what could it be...

Please, from what week can you feel fetal movement?...

The size of the fertilized egg corresponds to 3-4 weeks, according to hCG at 2.02 4539, at 4.02...

Pregnancy... but it’s too early to do the test and there’s no delay, but I’m already...

The hCG result is 20.9 mlu/ml. What is my gestational age? latest...

Please. The first day of the last menstruation is 04/20/2016. (conception by...

Accordingly, the period should be 8 weeks, but the ultrasound shows 4-5...

Discharge (brownish), what could this mean?...

The pregnancy calculator allows you to calculate the exact due date and find out what week of pregnancy you are currently in, as well as your expected due date. To calculate, select the date of the first day of your last menstruation at the top of the calculator and click on the "Calculate" button. After this, the calculator will automatically display your current week pregnancy and expected due date.

For each week of pregnancy, two are displayed. exact dates: start day and end day. The interval between them is exactly 7 days. You can scroll through the weeks of pregnancy using the arrows. A complete list of weeks from 1 to 40 is at the very bottom of the calculator. By clicking on them, you can also scroll through the slider to the desired week. The trimester of pregnancy to which each week belongs is indicated by Roman numerals at the bottom (at the slider) and in the upper right corner of the cells (in full list weeks). Also, trimesters are indicated in pink, orange and blue respectively. In general, the very concept of pregnancy trimesters is quite arbitrary and their boundaries are not clearly defined. We took as a basis the most common classification, in which the second trimester begins at the 14th week and ends at the 28th. Only your obstetrician-gynecologist can calculate trimesters more accurately after an ultrasound examination.

In the images you can see a rough illustration of the development of the baby inside the womb for each week. To the left of the images is short description fetal growth for a given week. You can find more complete and detailed information by clicking on the “More details” link, which is located under each description.

Method for calculating gestational age

The calculator calculates the so-called “obstetric” gestational age. It differs from the actual period by about two weeks. This method calculation is used in gynecology, because It is very difficult to calculate the exact day of conception. Therefore, the calculation is based on the first day of the last menstruation, the date of which, as a rule, every woman remembers. 280 days or 40 weeks are added to this day. Thus, during the first two weeks of the obstetric period you are not yet pregnant, because... ovulation has not yet occurred (based on medium duration menstrual cycle of 28 days). This method is not completely accurate, since some women ovulate late or early. But, in general, for most expectant mothers such a calculation turns out to be quite accurate.

In any case, we draw your attention to the fact that the pregnancy calculator allows you to calculate the due date using the most general formula, which does not take into account individual features your body. It cannot be used for self-diagnosis or any other medical purposes, since the results of its calculations are for informational purposes only. All precise calculations and any other manipulations should be carried out only by your attending physician.

Pregnancy is a time that requires a woman to maximum attention to your health.

This is the key to successful pregnancy, easy childbirth and the health of future children. But, as you know, the first weeks " interesting position“are almost asymptomatic.

Someone finds out about their situation after a couple of months, and then until the end of the term they worry about a couple of glasses of champagne drunk on corporate party. First of all, women who have recently learned about their pregnancy are concerned about the gestation period.

How to determine the exact duration of pregnancy in the early stages and how reliable are the available methods?

- the first thing a woman thinks about when she wants to make sure of her situation.

The tests are based on determining the presence of human chorionic gonadotropin in morning urine. This specific hormone that begins to be released after implantation of chorionic villi into the uterine mucosa.

It is an almost 100% guarantee of diagnosing pregnancy, and the due date can be determined by the concentration of the hormone.

The test result is traditionally presented by one or two stripes. In this way, the presence of pregnancy can be diagnosed, but its duration remains unknown.

And only with the help of a new product - digital test(for example ClearBlue Digital) - you can not only diagnose pregnancy, but also find out its duration.

If hCG is detected in the blood, ClearBlue Digital will determine its concentration, and from it the number of weeks that have passed since conception. The test result will be shown on a digital display. “-” means absence of pregnancy, and “+” indicates its presence. If a woman is pregnant, the “+” sign will indicate the number of weeks that have passed since conception.

The test provides 3 options: 1-2 weeks, 2-3 weeks and 3+ (more than three weeks after conception).

The test is so sensitive that it can be carried out not only from the day of the expected period, but also 3-4 days before this date.

However, you can determine the period without a test.

Determining the duration of pregnancy by the date of the last menstruation

If not digital home test confirmed the fact of pregnancy, but you want to know its duration, you can independently determine this by the date of your last menstruation.

This method is used in obstetric practice. Although in fact, the “traditional” gestational age is two weeks longer than real life embryo, because conception occurs approximately in the middle of the cycle.

For example, if your period was on February 10, then by the time of the delay (March 10 with a 28-day cycle) the period will be 4 weeks (1.5-2 weeks from the moment of conception).

Determining the period for hCG analysis

Human chorionic gonadotropin is a specific hormone that begins to be released after implantation of chorionic villi into the uterine mucosa.

The presence of hCG is an almost 100% guarantee of diagnosing pregnancy, and the due date can be determined by the concentration of the hormone.

The work of home tests (both digital and showing “two stripes”) is based on the determination of human chorionic gonadotropin in morning urine. There is also a blood test for hCG, which is performed in a clinical laboratory.

The sensitivity of the clinical test and its reliability are much higher than urine diagnostics.

A referral for analysis can be obtained from a gynecologist after a delay in menstruation is detected. Often the doctor pre-sets the pregnancy date after gynecological examination, because after the implantation of the embryo, the uterus begins to increase and each week of pregnancy corresponds to its size of the reproductive organ.

However, when going for analysis, you should remember that in some women the increase in hCG may differ significantly from statistical indicators. And this is not always associated with fetal pathology; it may simply be a metabolic feature. In this case, the deadline will be determined incorrectly.

Ultrasound diagnosis of pregnancy

The ultrasound method is the most reliable in diagnosing pregnancy, determining the gestational age and location of the fetus.

Opinions regarding this matter differ, so they try not to prescribe an examination without a good reason.

But ultrasound diagnostics indicated if there are some chronic diseases of the mother, as well as if the couple was treated for infertility or had experience of unsuccessful pregnancies.

Starting from 5th obstetric week(about 3 weeks after conception) ovum already visible on the screen.

Determine by its size estimated time pregnancy. In the early stages, a parameter such as SVD (average internal diameter) is used, and from the beginning of the third month it will be possible to determine the period by the coccygeal-parietal size (CTR).

Measurement of basal temperature

If a woman planned her pregnancy, recorded and knows her own physiological cycles, then another home diagnostic method will be available to her. You can continue after the date of ovulation and possible conception.

Above 37°C can most likely indicate pregnancy.

Measuring basal temperature should be done while lying down, after sleep, preferably at the same time, otherwise the data will be uninformative.

All measurements must be entered into a special table, and then a graph of basal temperature must be plotted. So here embryonic period your pregnancy will be equal to the number of days following the day when the basal temperature became above 37.

Finding out your pregnancy date as early as possible is the dream of all women, because your plans for the future largely depend on it. If you want to quickly confirm that you are pregnant, do a home test and then get examined at a antenatal clinic.

The sensitivity of tests and the quality of ultrasound diagnostics are constantly improving; you will receive a result that has a high degree of reliability.