Calculate the date of delivery by monthly - all ways


Calculation of the expected date of delivery (DA) can be done in several ways, and each of them will be only indicative. Every gynecologist has a “favorite” way he relies on. But the deviation of the date of delivery from the calculated one is a variant of the norm.

The proposed method - on the first day of the last menstruation. Suitable for women with a regular cycle of 28 days.

How else can you know the gestational age and the date of birth

1. In the first trimester, it is possible to find out the gestation period with high accuracy directly at a gynecologist's appointment. He will determine the term without any analysis, just by the size of the uterus. In the 2nd and 3rd trimesters this will not work out anymore.

2. Calculate the date of birth by the date of ovulation.

What is ovulation and how to determine it, read here.

You can also create your own ovulation calendar on our website.

To make calculations using this method, you need to add 280 days to the ovulation date.

You can use as an initial data the date of sexual intercourse (consider only that the fertilization of the egg can occur on the 2nd, or even on the 3rd day after it.

3. Hardware calculation of the gestational age and the date of delivery using ultrasound. This period can be determined with an accuracy of 1-3 days.

With the help of ultrasound, a specialist can observe the condition of the fetus, placenta, the position of the baby’s head relative to the entrance to the pelvis, the opening of the cervix and other important parameters. That is why this method is highly accurate.

Calculation of the term of delivery by monthly

Calculate the date of delivery by monthly easiest. No additional equipment, complex calculations, attention to sensations are needed. The approximate date can be calculated by a calculator, as well as by simple independent calculations. To the number in which the last menstruation began, it is necessary to add 7 days, and then subtract 3 months. For example, the monthly began on September 1, 2016. Adding a week, we get September 8. We subtract three months, change the year to the next, and the expected date of the happy event, June 8, is obtained.

A common question is why exactly this point of reference? After all, conception happened later (or earlier), and where is menstrual bleeding? From this date is considered the so-called obstetric gestational age. The stage of the life of the egg from the beginning of its development to maturation (ovulation) is taken into account. According to this method, the process of waiting for a child lasts 10 months, 40 weeks, or 280 days. This is two weeks more than when calculating the term of the birth of a baby by conception.

This technique is used by all obstetrician-gynecologists. Despite its relativity, it is as accurate and convenient for orientation. It is precisely at her that they look around first of all when the pregnancy is delayed or, on the contrary, tends to be resolved earlier.

Calculate the coveted day can be at any moment waiting for the child. The main thing is for a woman to remember when her last menstruation began before pregnancy.

Other methods of calculation

How to calculate the date of delivery? The answer is quite simple - by all known methods. Each woman’s birth card indicates the estimated number of times her baby is born, as determined by several techniques. To reliable (except for the "menstrual" method) include:

  • by ovulation,
  • on ultrasound diagnostics,
  • on registration of the first movement,
  • on objective inspection.

Determination by ovulation

Calculate the date of delivery for the monthly as easy as ovulation. Only in this case, not the first day of bleeding, but the middle of the cycle is taken as the main point of reference. If a woman lives in a cycle of 28 days long, respectively, the countdown starts from 14 days. The baby will be born approximately in 38 weeks.

But again, the question arises: what to do if “that” sexual intercourse did not occur on the day of the maturation of the egg cell? Is it possible to calculate the date of birth for ovulation?

Yes. The thing is that the sperm, entering the woman's body, "are waiting for the right moment." If the sperm is cast to this very moment, the germ cells will wait. They are able to survive in the conditions of the female body for 2 to 4 days (on average). But if the seminal fluid got into the vagina after ovulation, then pregnancy probably will not come. The calendar method of contraception is based on such calculations.

However, life can not be ordered, when to emerge, and when - no. There are cases when sperm survived for a week! It happens that pregnancy occurs during menstrual bleeding (the child is born, of course, Chuck Norris. Therefore, this technique also can not claim to be exclusively true, although it works in most cases. Most often, ovulation calculates the estimated day of delivery only once, on the initial examination.Later, the exact date of maturation of the egg is forgotten, and there is a risk of error.

Definition by ultrasound

It is worth noting that a specialist in ultrasound diagnosis can not reliably determine the duration of pregnancy. Nonsense? Not really. The fact is that the doctor can only state the fact: the development of the fetus corresponds, for example, to the 20th week of pregnancy. Later this conclusion is compared with the estimated period calculated by other means. It is concluded whether there is a lag in the development of the fetus, whether it is possible to diagnose a missed abortion, or if everything is in order.

Accordingly, it is also not possible to reliably calculate the date of birth by ultrasound. The exception is early terms. In the period of up to 3-3.5 months, all embryos develop in the same way, they do not have individual features (if this is the norm). Only later some start to grow faster, adopting the constitutional properties of parents, others - more slowly. That is why in the first weeks of pregnancy, the expiration date with the help of the ultrasound machine can be set fairly accurately.

Objective determination by a doctor

Predict when a woman will give birth, can an experienced obstetrician-gynecologist. At the beginning of the consultation, he determines the approximate period of monthly, and then conducts an external examination. Every week the uterus grows in size and grows, reaching certain external landmarks. These include, first of all, the pubis and navel. Contrary to the narrow-minded logic, the bottom of the uterus is not at the bottom, but at the top. Imagine an upside down pouch or a normally oriented, half-blown balloon. Named "reference points" the uterus reaches its very bottom. It is easily felt through the skin and abdominal muscles, especially in fragile girls.

Already from the end of 3 months you can determine the height of the bottom of the uterus. At first it is hidden behind the pubis, by the 14th week it comes out from behind the bosom, tending to the navel, and reaches the middle of the distance at 16 weeks. Exactly under the navel, it is located in the period of 6 months (24 weeks), increasing more and more.

The accuracy of this technique is difficult to assess. On the one hand, the patterns of change in the size of the uterus are the same for all. On the other hand, firstly, each doctor has his own hands, and he feels them differently than the other doctor. Secondly, the degree of stretching of the uterus depends largely on the size of the fetus. And it can vary significantly for different women. It is also worth noting that in the later stages of pregnancy this definition is difficult due to the significant stretching of the organ and the high size variability of the fetuses.

Definition of the first stir

Each woman can independently calculate the date of delivery monthly. And for this, it is not required, as already mentioned, special attention to your body - just keep the menstrual calendar carefully. But the method that offers to calculate the approximate time of delivery, focusing on the feeling of perturbation, asks for careful attitude to their sensations.

It is believed that with the first movement of the fetus in the womb, the strength of the bond between mother and child is strengthened a hundredfold. Women finally realize that inside them is a new life. In this regard, in most cases, the very first movement of the fetus is of great importance.

Normally, the baby begins to move as early as 3 months. However, he is still too small for his mother to feel his movements. The truth is sometimes, I must say, suspicious ladies confuse digestion with the movements of the crumbs. But truly a woman begins to feel the "presence" of the baby at 20 weeks, if she gives birth for the first time, or at 18, which refers to the multiplying. It is from this period in the generic exchange card at each visit of the woman to the consultation that it is indicated whether she feels the movement of the fetus.

Calculate the date of birth at the first stir is simple. To the day when Mommy first felt her crumb, you need to add:

  • 20 weeks if the firstborn is expected
  • 22 weeks if the woman has more children.

Thus, in the early stages, the estimated number of an important event is best determined by ovulation or by ultrasound. In the second trimester, the doctor will best deal with this task during the examination. But by the second half of pregnancy you need to listen to the movements of the baby.

Calculation of the date of delivery after IVF

In vitro fertilization refers to assisted reproductive technology. To carry out this procedure, a couple is prepared for a very long time. A man and a woman must pass a lot of tests, cure all somatic (“non-sexual”) pathology, lead a correct lifestyle. In addition, prior to the procedure for collecting the ovaries, the woman’s ovaries stimulate hormone therapy.

For monthly doctors are not oriented, they "set" their own cycle. At the same time, not one and not two, but ten eggs are ripening. This procedure is called regulated ovulation. This means that its date is known exactly, because provoked medication. In this case, the most correct way to consider the moment of appearance of a new person is from ovulation. The date of embryo replanting is known for certain. Usually pregnancy occurs within 12-14 days after the procedure of replanting. Thus, the calculation can be conducted from this day.

The fact is that there are no features of the baby’s waiting period in this case. The only difference is that such pregnancies are most often multiple births, therefore they are resolved somewhat earlier.

Calculating the date for an irregular cycle

Calculate the date of delivery by menstruation is problematic if a pregnant woman has a menstrual problem. In one month, the cycle lasts 25 days, and in the other - 35, and how can you calculate it?

In this case, this method of calculating the coveted day is not suitable. You can try to determine the date of ovulation - the average duration of the menstrual cycle per year is taken as a basis, and the time of maturation of the egg is calculated. However, this answer is quite far from the truth. Therefore, the best way is considered a combination of different options - orientation to ultrasound and the approximate duration of pregnancy.

But if the cycle is regular, but lasts more than 28 days, then there should be no difficulties. Ovulation somehow happens in the middle of it, so the “X-day” is simply calculated, and further calculations are carried out on it.

Normal term is when?

Urgent delivery is a delivery that occurred between the 37th and 41st (40 weeks and 3 days) gestational weeks. Moreover, in obstetric practice, the main method is the calculation of monthly. The term “urgent” is used in this case not in the sense of “emergency, urgent”, but as a childbirth that occurred “on time”.

Shortening or lengthening the waiting period for the crumbs is almost always a deviation from the norm. Exceptions:

  • genetic predisposition (deviation can be in any direction),
  • multiple pregnancy (childbirth begins earlier).

Premature labor

Earlier, about 35% of babies are born. For some of them, early birth does not matter. However, often children who see the world too early have serious health problems, need resuscitation and then special care.

Childbirth is very early (22-27 week), early (28-33 week), actually premature (34-36 week). In Russia, a live born baby is a baby born at a time later than 22 weeks, weighing more than 500g, with a body length of more than 25 cm and having one of the signs:

  • breath,
  • heartbeat
  • cord pulsation
  • muscle contraction.

Premature birth may be due to:

  • by stress
  • stimulation of labor activity (sexual intercourse, climbing stairs, taking Oxytocin),
  • pathology of the cervix, including cervical insufficiency,
  • inflammatory process
  • high water
  • abortions and miscarriages in the past
  • and etc.

It happens that an error occurred while trying to calculate the date of delivery by monthly. Scarce, born on week 36, actually grew and developed already 38. The key role is not played by what date was originally set. The judgment of the urgency or premature delivery is based on the state of the baby.


If the baby was not born on the 3rd day of the 41st week, then the pregnancy is considered postponed. This condition is more favorable than prematurity, because all organs and systems are already developed to the required state. However, the longer the baby is in the uterus, the larger its size, and, consequently, childbirth for a woman will be more traumatic. In addition, long-term presence of the fetus in the uterus helps to reduce the intensity of uteroplacental blood flow, causing oxygen starvation in the fetus.

The reasons for the late completion of the process of carrying a child can be:

  • dysfunction of the placenta,
  • endocrine pathology in mom,
  • large fruit,
  • wrong psychological attitude, fear of childbirth.

Thus, there are many options to find out when to wait for the appearance of the baby. You can calculate the date of delivery by month, a calculator to help you, you can use any other method described. The most important thing is to carefully monitor your body, not to allow stress, failure of the regime, as well as carefully prepare for pregnancy. Then the process of waiting for the child will be easy, and childbirth will come on time.

My name is Victoria Soldatova and I welcome all visitors to my blog. Children are millionaires.

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How to determine when childbirth comes (PDR)

If the delay in menstruation is small and there are no complaints about feeling unwell, then you should not rush to an appointment at the antenatal clinic. But internally, the feeling already tells you that a miracle happened and soon you will become happy parents of a wonderful baby. Any woman in this position seeks to get an answer to the question: when exactly is the time for delivery? Our service allows for a few minutes to determine the exact date of birth of the unborn child.

Calculate the date of delivery online

At the heart of any method of calculating the date of intended delivery is the idea of ​​a normal gestational age, which usually lasts about forty weeks (in some cases, a deviation by several weeks is also not a pathology). The starting point is the beginning of the last menstruation, and it is likely that the expected event will take place exactly in 280 days or 40 obstetric weeks.

With the help of the online calculator presented on the site, you can easily find out the likely date of the upcoming delivery. All that is required of you is to enter the necessary data into the appropriate calculator windows, and the computer performs the necessary calculations. The principle of calculating is very simple: the start date of the last menstrual bleeding and the traditional 280 calendar days are summed up.

The received date is approximate, corresponding to ideal medical indications. The actual time may vary slightly depending on the individual characteristics of the woman, her state of health and the general course of pregnancy.

Calculate the date of delivery by the date of conception

Not every woman knows exactly the day when conception occurred, so doctors cannot reliably determine the so-called “embryonic” gestational age. However, if the time of fertilization is known, the results of the calculation of the time of birth will be much more accurate, because each child needs the same period for full intrauterine development. In such cases, you need to add 280 days again, this time to the date of conception.

When calculating the date of birth after the day of fertilization, minor errors are allowed, because pregnancy could not occur on the day when the corresponding sexual intercourse occurred. Studies show that conditions in the vagina are quite favorable for sperm, so they can be here for several days until it merges with the egg. The error is from one to three days, but no more. Thus, the date of conception determined by a similar method is also tentative.

Calculate the date of delivery for ovulation

Determine the date of the birth of the baby can be using the calculation of the day of ovulation. Такой способ подходит не для всех, ведь лишь незначительное количество женщин тщательно следит за своим менструальным циклом и тем более – ведет календарь овуляций. Если известна хотя бы приблизительная дата овуляции (при постоянном цикле в 28 дней она выпадает на его середину), можно получить более-менее точную дату родов. Для этого необходимо прибавить к дате овуляции 280 дней.

Of course, the most accurate results can be obtained if you have the maximum amount of input data. The best option is to combine all the presented methods for calculating the date of delivery. But in any case, a few days of waiting is not a big problem, because the main thing is the birth of a healthy child and the subsequent pleasant chores.

Video: How to determine the date of birth.

Benefits of using a pregnancy calculator:

  • Every woman with the onset of pregnancy raises many questions. When will the belly grow? When will the baby start to move? When do you need to get registered in the antenatal clinic and when can I leave on maternity leave? When to wait for the birth of the baby? All these questions can be answered on our website. We described all changes in the mother’s and the child’s body by weeks, indicated all significant events,
  • With the help of a pregnancy calculator, you can find out the exact dates of each trimester, significant dates (conception, childbirth, prenatal leave),
  • The doctor at the reception will ask about changes in the state of the woman. With the help of a calculator, it is very convenient to look at what to pay attention to, in what time these or other symptoms should appear,
  • An obstetrician-gynecologist will necessarily draw up a survey plan, tell you what week you need to take certain tests, make ultrasound and other instrumental examinations. The electronic pregnancy calendar is a convenient reminder of exactly when and why you should go to the consultation. We tried to explain why each analysis is performed and how to evaluate its results.

Online pregnancy calculator is a convenient service that helps a woman to have a clear idea of ​​the course of pregnancy and the sequence of events.

* An approximate calculation based on the average values ​​of the duration of the cycle and the beginning of ovulation - plus 14 days to the beginning of the last menstruation.