Use our EDA (estimated due date) calculator to calculate the estimated date of birth of your baby. The calculation can be made by the date of conception, or by the date of the last menstruation. Select the appropriate option and enter the original date. As a result of the calculation, you will receive the cherished date, as well as accurate calendar pregnancy with comprehensive information about fetal development and medical indications for each week. The calculation results can be saved by email or printed.
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Gestational age- one of the main components that a gynecologist needs to know about for proper management of pregnancy. After all, on the basis of this, the doctor will prescribe necessary examinations, tests, routine ultrasounds, monitor intrauterine growth and fetal development, will reveal during possible violations. In addition, determining the due date allows you to quite accurately calculate the date of birth and the date maternity leave. It is necessary for the woman herself to know the duration of her pregnancy in order to mentally prepare for childbirth, have time to prepare a room or corner for the unborn baby, and purchase everything for him necessary supplies and clothes.
In this article we will look at how to determine the duration of pregnancy.
Calculate by monthly
A woman who came to register with antenatal clinic, the gynecologist first asks the question about when her last period began. It is from this date that he begins to keep a record, despite the fact that fertilization has not yet occurred at this time. It is known that fertilization of the egg occurs on the day of ovulation, which occurs in the middle of the menstrual cycle. This method of determining the gestational age is called “obstetric”.
An online calculator will help determine the period:
How to determine by date of conception
It is known that conception occurs only during ovulation within 24 hours after the egg leaves the follicle. And the viability of sperm in the female genital tract is up to 3 days. It turns out that the date of sexual intercourse does not always coincide with the date of conception.
Ovulation occurs in the middle of the menstrual cycle. A woman who monitors her menstrual cycle can quite accurately calculate the onset of ovulation. In addition, many people at this time have characteristic features: aching pain in the lower abdomen, breast swelling, irritability, copious discharge from the vagina, increased sexual desire.
It is worth noting that only those women who have regular menstrual cycle.
Online calculator:
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How to calculate using ultrasound
It is possible to find out the gestational age using the results of an ultrasound examination (ultrasound). It is determined according to the size of the fetus. The first ultrasound of the expectant mother is performed at 12-14 weeks, but at this time it is no longer possible to accurately determine the period, since the development of the fetus occurs individually in each woman. It is possible to find out the age of the fetus by ultrasound with an accuracy of one day only in the first weeks after conception.
Determination during examination by a gynecologist
A gynecologist can determine a woman's gestational age by the size of her uterus during a gynecological examination. At 5-6 weeks, the size of the uterus can be compared to a chicken egg, at 8 weeks - to a goose egg. Later, it will be more difficult to determine how many weeks a woman has based on the size of her uterus.
Find out the due date by the first fetal movement
In the first pregnancy, a woman begins to feel fetal movements at 20 weeks, in the second - at 18 weeks. But this method does not always allow one to determine the period, since some expectant mothers may feel the first movements of the fetus earlier or later than the indicated weeks - some, due to the structural features of the body, cannot feel the movements of the fetus, others confuse the work of the intestines ( increased gas formation) with movements.
Determine by hCG
Human chorionic gonadotropin (hCG)- one of the most important indicators, indicating the onset of pregnancy and its normal development. The hormone begins to be produced in the female body after implantation of the embryo into the wall of the uterus. HCG level in the blood allows you to find out the approximate age of the fetus. With multiple pregnancy, the level of the hormone in the blood increases in proportion to the number of fetuses.
| Week of pregnancy | HCG level, honey/ml |
| 1 - 2 | 25 - 156 |
| 2 - 3 | 101 - 4870 |
| 3 - 4 | 1110 - 31500 |
| 4 - 5 | 2560 - 82300 |
| 5 - 6 | 23100 - 151000 |
| 6 - 7 | 27300 - 233000 |
| 7 - 11 | 20900 - 291000 |
| 11 - 16 | 6140 - 103000 |
| 16 - 24 | 4720 - 80100 |
| 21 - 39 | 2700 - 78100 |
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Pregnancy term calculator
For many women, the feeling of an upcoming or already begun pregnancy occurs before the test shows two lines - that is, even before the actual delay. Scientists cannot yet give an explanation for these true premonitions, but the concept of Early Pregnancy Factor has already been introduced into the scientific lexicon, which describes chemical reactions the maternal body in response to the accomplished conception after just a few hours. Currently, there are already tests for identifying the Early Factor hormone in the female body, but due to their significantly high cost, these tests are not produced on an industrial scale.
On average, birth occurs 10 obstetric months (280 days) after pregnancy, when the baby is ripe for birth. However, it should be noted that 280 days is the conditional number of days of bearing a child. All female organisms are different, and all babies mature differently in their mother’s tummy. Some will need 280 days, while others will be “already ready” in 240 days. Only 2% of newborns are born on a precisely calculated day. Most children are two weeks earlier, or several days later than the appointed time. The duration of pregnancy and childbirth is calculated based on the date of the start of the last menstruation.
If we take into account all the changes that occur with the baby almost every day during pregnancy, and especially the first trimester, then in general these processes in importance and complexity, in depth, can be compared with the birth of a new universe. Every day of the little baby inside you is not just a step, it is a huge leap, a breakthrough forward. The birth of a new life, despite the scale of achievements, does not require any external efforts... everything happens under the cover of secrecy. After all, the woman herself learns that conception has occurred only after some time. Thanks to modern technology, scientists have been able to study a little great secret birth is where EVERYTHING begins. Enter your data and flip through the pages of the calendar of human life development throughout pregnancy. Believe me, amazing discoveries await you!
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Each future mom wishes and strives to ensure that the pregnancy proceeds without complications, and that the baby is born strong and healthy. To do this, you need to correctly determine the date of conception and the timing of pregnancy.
It is very difficult to say with accuracy on what day conception took place, even for gynecologists with extensive work experience. But you can find out the approximate date. There are several ways to determine it. Let's look at these methods, as well as their pros and cons.
1.You can determine the period of conception by the date of your last menstruation. This calculation method is suitable for women with a regular menstrual cycle. To do this, you need to count two weeks from the first day of your last menstruation. The method of this calculation is explained by the fact that conception can occur only after ovulation. For example, if your cycle lasts 26 days, then your ovulation period will be between 11-15 days. With this method of calculation, an error of 1-2 weeks is allowed.
By the date of the last menstruation, you can find out the approximate date of birth. The following 2 methods are very popular and simple:
— 280 days are added to the date of the first day of the last menstruation. The resulting month and date will be the approximate start date birth process.
- Nägel's formula. From the date of the most recent menstruation, subtract 3 months and add 7 days.
2. If you have forgotten when your last period was or have an irregular cycle, an ultrasound will come to the rescue in this situation. On initial terms pregnancy (up to the 7th week), all embryos have the same rates and signs of development. Exactly ultrasonography in the early stages, will help you find out the most accurate date of conception. After 7-8 weeks, all babies begin their individual development, therefore, the longer the pregnancy, the more difficult it is to determine the date. Ultrasound examination not only provides the most accurate indicators of the period of conception, but also helps in identifying pathologies.
3. All women, suspecting that they are pregnant, immediately rush to the gynecologist for an examination. But, unfortunately, the doctor will be able to tell a more accurate date of fertilization only if early pregnancy.
From the second trimester, doctors can determine the date of pregnancy by the length of the uterus. As you know, with each subsequent week of pregnancy, the uterus increases in size by 1 cm. Lying on a couch or gynecological chair, the doctor feels the uterus and uses a centimeter to determine its size.
There is also a special table from which you can find out the gestational age by the location of the uterus relative to the womb and navel.
— At 12 weeks, the uterus is located closer to the upper edge of the womb.
- At 14 weeks of pregnancy, the uterus is located below the womb at a distance of about two fingers.
- At week 16, the location of the uterine fundus is between the navel and the womb.
— At week 20, the uterus drops below the navel.
— At 24 weeks, the uterus is located at the level of the navel.
- At 28 weeks, the fundus of the uterus is above the navel at a distance of two fingers.
- At 32 weeks, the length of the uterus reaches 27-30 cm and is located between the short part of the sternum (xiphoid process) and the navel.
— At 36 weeks, the uterus is positioned so that it supports the ribs.
- At 40 weeks, before the birth itself, the baby changes its position and prepares to be released, so the uterus takes a position between the navel and the xiphoid process.
Again, this method of determining the period has its own errors, since the body of each pregnant woman has individual characteristics.
4. Exact date pregnancy can be determined by calendar method. The calendar method includes measuring basal temperature over several cycles. Temperature should be taken every morning at the same time. The data is recorded in the form of a graph, according to which the day of conception is determined. This method also includes those cases when a woman has rare sexual intercourse and knows the date of her last intimate relationship.
5. You can determine the date of conception by taking an hCG test. Blood is taken from a vein to analyze the level of human chorionic gonadotropin. This method of calculation is inaccurate even at the initial stages. This analysis is carried out more to identify pathologies in the fetus and to identify the pregnancy itself.
6. The gestational age is determined by the very first movement of the baby in the womb. Women who give birth for the first time should feel the first movement strictly at 20 weeks. And those giving birth for the second or third time feel the first movements 2 weeks earlier, that is, at 18 weeks. This method of calculating the due date is also not very accurate, since the course of pregnancy is a purely individual process. Many expectant mothers often confuse the baby's first movements with bowel activity. This is explained by the fact that almost all pregnant women have increased gas production.
7. The approximate date of conception can be determined by the size of the abdomen. With this method of determination, it is necessary to take into account the woman’s weight and physique. The abdominal volume is measured using a centimeter at the level of the navel.
The gynecologist can calculate the most accurate date by collecting data from all of the above indications. If the pregnancy is multiple, labor may begin 2-3 weeks earlier than the expected date.
True and obstetric pregnancy periods
The true gestational age is calculated from the last release of the egg or so-called ovulation, which occurs 2 weeks after menstruation. Let us remind you once again that determining the exact date of ovulation is possible only with a regular menstrual cycle. Obstetric period is calculated from the first day of the last menstruation.
The difference between these periods is that the true period is 2 weeks less than the gynecological one.
Every expectant mother must remember that plans for the birth of a long-awaited baby may not coincide with the calculations of even the most experienced gynecologist.
Why do pregnant women and doctors need to know what stage of pregnancy it is? Firstly, to determine the due date, secondly, to adequately monitor the baby’s development, correcting possible developmental delays in a timely manner, and thirdly, to determine the date of maternity leave.
I would like to make a reservation right away that there is a difference between obstetric and true pregnancy periods. Obstetricians begin to count the gestational age from the 1st day of the last menstruation. This is quite justified, because from this moment the egg begins to mature, which will later be fertilized by a sperm, a zygote is formed and implanted in the uterus, a fertilized egg with an embryo, and then a fetus (after 12 weeks of pregnancy) will begin to develop. The duration of pregnancy from the first day of the last menstruation until birth is about 10 lunar months or 280 days or 40 weeks. However, each fruit has its own term intrauterine development- from 37 to 42 weeks. This depends on many factors, but is primarily determined genetically. It is necessary to ask at what stage of pregnancy the patient herself, the father of the child was born, and until what period the pregnancy of the maternal relative was carried to term.
The true pregnancy period lags behind the obstetric date by two weeks - it is counted from the day of ovulation and conception. Thus, to determine obstetric period You need to add two weeks to your actual pregnancy.
How to find out the gestational age by ovulation and date of conception
Ovulation is the very period of the menstrual cycle when conception of a child can occur. During ovulation from a woman's ovary fallopian tube a mature egg is released and “waits” for sperm there. Unprotected sexual intercourse at such a time is more or less healthy woman and men will most likely lead to pregnancy. The date of ovulation is used to determine the duration of pregnancy.
A woman ovulates around the middle of her menstrual cycle (but not every month). If your menstrual cycle is 28 days, then ovulation will occur somewhere on the 14th day, with a 35-day menstrual cycle - on the 17-18th day of the cycle. The exact duration of pregnancy should be counted starting from the day of ovulation.
Ovulation can also be determined at home, using special tests sold in almost any pharmacy, or by regularly measuring basal temperature(temperature in the rectum). Throughout the first half of the cycle it will remain at approximately the same level - below 37 degrees. The day before ovulation it will decrease slightly. And on the day of ovulation and on all subsequent days you will maintain a level of 37-37.2 degrees. Thus, you can calculate the duration of pregnancy (), if it began in the menstrual cycle when you determined your ovulation.
There are women who can determine their ovulation without any tests or temperature measurements, simply by subjective feelings– pain in the lower abdomen, increased libido, increased amount of vaginal discharge. It is easy for such sensitive women to determine the duration of pregnancy on their own.
Most exact way Determining the gestational age by the date of ovulation is an ultrasound. This is the only way to accurately see ovulation. But it’s problematic to go for an ultrasound every day for a week, or even longer. And financially, such “pleasure” will not be available to every woman. Trying to determine your ovulation only so that you can later accurately calculate the duration of your pregnancy is inappropriate. There are more simple ways calculating the gestational age already, in fact, after the onset of an interesting situation.
The number of days (weeks) at the time of examination of the pregnant woman is counted from the first date of the last menstruation. To determine the day of birth, add 280 days (10 lunar months) to the first day of the last menstruation or use the Naegele formula: subtract 3 months from the start date of the last menstruation and add 7 days. This method cannot be used in women with irregular menstrual cycles.
Determining the gestational age by gynecological examination.
If you come for an examination to a gynecologist in the first weeks of pregnancy (at 3-4 weeks), then it will not be difficult for the doctor to accurately determine the gestational age. In this case, it is performed based on the size of the uterus. For example, at 4 weeks of pregnancy the size of the uterus can be compared with chicken egg, at 8 weeks - with a goose egg. An experienced gynecologist is able to determine the gestational age through a vaginal examination with an accuracy of one day. It will be difficult to accurately determine the gestational age beyond 8-12 weeks simply based on the size of the uterus. Since starting from the second trimester of pregnancy, the size of the uterus may differ in women at the same stage of pregnancy.
Determination of gestational age by ultrasound.
Of course, here, as with the previous method, much depends on the qualifications of the doctor who interprets the results. Ultrasound data obtained before the 12th week of pregnancy are considered the most correct for determining the date of expected birth. At this stage, determining the gestational age is based on measuring the fetal egg and its average internal diameter.
In the second and third trimesters, the gestational age is determined based on the determination of such parameters as fetal head circumference, average diameter chest and fetal tummy, fetal abdominal circumference. The most reliable information is considered to be obtained by measuring the circumference of the baby's head.
However, in general it is believed that late dates During pregnancy, the error in determining the due date using ultrasound increases. This is understandable: after all, each child develops individually, and at the end of pregnancy, the size of the fetus, which the doctor focuses on in his calculations, can vary significantly depending on the characteristics of a particular child.
With all the variety of methods for determining the date of the upcoming birth, there is no one “absolutely accurate” method, as we have already said. Therefore, we can say that more or less precise definition the timing of the upcoming birth is possible if all the data obtained are not contradictory, but complement and reinforce each other.
Although even in this case, the date of birth may shift by one or two weeks in one direction or another due to the fact that term birth (that is, birth at term) can occur in the period from 38 to 42 weeks of pregnancy.
Determining the gestational age by the first movement.
Primipara women begin to feel the first movements of the baby at 20 weeks of pregnancy. Multiparous women a little earlier - at 18 weeks. Gynecologists recommend that a woman remember the date of her first movement and be sure to include it in the pregnant woman’s dispensary card. This is of great importance when determining the due date of pregnancy and childbirth. For example, in order to determine the date of birth, it is necessary to add 20 weeks (or 4.5 months) to the date of the first movement; for multiparous women, it is necessary to add 18 weeks or 5 months.
But this method of determining the gestational age is not always correct. There are women who, even in their first pregnancy, feel the baby’s movements much earlier due date at 20 weeks, at 17 weeks, or even earlier. Such early movements are especially often observed in skinny women. There are women who feel the first movements 2 weeks later than expected.
Doctors have their own opinion regarding such early movements and setting the gestational age based on them. Most experts believe that women before the due date do not feel the baby’s movements at all, but the “work” of the intestines. After all, as you know, most pregnant women suffer from increased gas formation...
Determination of gestational age by measuring the length of the uterus and fetus.
You can calculate the gestational age in a more complex way. Only a gynecologist can make such a calculation. You are unlikely to succeed on your own. So, in order to measure the length of the uterus, a woman lies down on the couch and straightens her legs. It is necessary to empty it first bladder, otherwise errors in determination are possible the right time pregnancy. The length of the uterus is measured using a centimeter tape or a pelvis gauge. Usually the length of the uterus is equal to the number of weeks. For example, the length of the uterus is 36 cm, which means the gestational age is also 36 weeks.