When is the date of birth determined by ultrasound

Every expectant mother is interested in when the baby is born. There are several ways to determine the date of birth – by ultrasound, day of conception, the menstrual cycle and others.

There are many reasons why a mother cannot wait to find out the birth date: someone hopes that the baby will become a “gift” for her husband’s birthday, other women who are interested in astrology want to know who their children will be according to the horoscope

and some mothers will think about it in advance a name for the newborn, which will have a sacred meaning and correspond to a certain number of the calendar. Whatever the future mother’s motive, unfortunately, it is impossible to reliably know the baby’s birthday.

How to find out the exact date of delivery?

From the first weeks of pregnancy, future parents are interested in when they first see their baby. I especially want to calculate the birth date of a baby for a woman, so she is looking for different ways to calculate the date of birth: she uses a calculator, looks at the calendar .

It is practically impossible to know exactly the day when the baby is born into the world, because a lot of both external and internal factors influence this. For this reason, doctors have established a concept such as the estimated date of birth (DA) which allows you to determine the approximate gestational age and birthday of the baby.

There are two types of gestation countdowns:

  • obstetric – it is considered according to the phases of the menstrual cycles, starting from the first day of the last menstrual period, so the period is 40 weeks;
  • true – implies the onset of fertilization during ovulation, which occurs in the middle of the month, and this suggests that the true period is two weeks shorter than obstetric and equal to 38 weeks.

Often women calculate the date of birth by adding a period of 9 months to the day when conception probably occurred. This calculation method is not reliable, since physiological pregnancy does not last 9, but 10 lunar months, which corresponds to 280 days.

Medical practice shows that only a small part of children are born on the day of the expected date of birth, while other babies are born at different periods: someone earlier, someone later. We should not forget that pregnancy is considered full-term from 38 weeks, and the normal period of intrauterine development can last up to 42 weeks, after which the fetus is considered to be postponed.

No methodology for calculating DA can give a 100% answer to the question of when the baby will be born.

Below are the most common methods for determining the date of birth:

  • On the day when conception occurred.
  • According to the results of ultrasound examination.
  • According to data obtained during the examination by an obstetrician-gynecologist.
  • By the date of the last menstrual cycle.
  • At the time of the first movements of the child.
Date of birth at conception

The easiest way to determine the date of birth is the method of calculating the day of conception .

The female menstrual cycle consists of three periods:

  • Follicular phase. It starts from the first day of menstrual bleeding and lasts until ovulation. During this period, a follicle forms, from which the female reproductive cell will subsequently be released.
  • Ovulatory phase. The exit of a mature egg from the follicular membrane. Before ovulation begins, a sharp increase in the concentration of luteinizing hormone occurs. It is on his definition that pharmacy tests are based that help determine the release of an egg.
  • Luteal phase. After the female reproductive cell emerges, a corpus luteum forms – the body prepares for conception. If this did not happen, then the detachment of the covering layer of the uterus begins, which is manifested by menstrual bleeding.

Fertilization is possible only during ovulation, when an egg matured to a meeting with a sperm is released from the follicle and leaves the ovary into the fallopian tube. The oocyte is viable for 1-2 days, therefore conception is possible only on certain days of the month, and if a woman knows when ovulation occurred, this will allow her to calculate the approximate date of delivery.

The average cycle time in women ranges between 28 and 35 days. Ovulation almost always occurs in the middle of the cycle. However, without special tests or daily monitoring of the condition, it is impossible to determine the moment the egg enters the fallopian tube.

Some women are very sensitive to any changes that occur in their body, therefore, subject to regular monthly monitoring, they can determine when ovulation occurs.

There are certain signs for this :

  • increase in basal temperature;
  • changes in the amount and viscosity of cervical mucus;
  • discomfort in the lower abdomen or in the projection of the ovaries;
  • increased libido.

Knowing when fertilization occurred, you can calculate the estimated date of birth. To do this, 280 days should be added to the day of conception.

When a woman does not know the day of ovulation, you can simply calculate the middle of the duration of the calendar cycle and add 40 weeks to this number. However, in this case, the baby’s birthday will be even more inaccurate than with the previous method.

The chances of a more accurate calculation of the DA are increased if you know the exact day of sexual contact, and it was single in the last cycle. It should be understood that the date of proximity and fertilization may also not coincide, because sperm can live in the female body for 3 days.

Date of birth by ultrasound

The most accurate date of birth is determined by ultrasound, and this can be done already in the early period of fetal development – in the first trimester. An ultrasound transducer transmits the image from the uterine cavity to the monitor, and the doctor-diagnostician, by what he sees in the image, can tell when the conception occurred and how long the woman is pregnant. This can be ascertained by signs of fetal development, as well as by the state of the uterus.

At later dates, it is also possible to determine the date of birth using ultrasound diagnostics, however, for this, the doctor draws attention to the fetometric parameters:

  • the circumference of the fetal head;
  • coccygeal-parietal size (KTR).

We must not forget that starting from the second trimester, all children develop at a different pace and have different sizes: someone is larger, someone is smaller, one baby has a big head, another baby is tiny. Yes, and the weight of the baby at birth can radically differ: from 3 to 5 kg. Although the divergence of values ​​is large, all these characteristics are suitable for the definition of the norm.

With early ultrasound diagnostics, the age of the embryo is usually determined to be 2 or 3 weeks longer than the actual one, which transfers the PDD to an earlier date. When he comes up, and the woman still carries the baby under her heart, she begins to worry that the pregnancy is postponed, although, most likely, the baby’s birthday was incorrectly calculated.

Naturally, all women are different: one expectant mother has large parameters, the other looks miniature, so it is absolutely logical that their children will differ in size. In a thin, short pregnant woman, the results of late ultrasound in the second and third trimesters may suggest a later date when the baby is born. For this reason, ultrasound data in the second half of pregnancy should not be interpreted to determine the day of birth. It is necessary in order to see how the child develops and whether everything is in order with him.

How accurate are the methods?

Reliably determine the date of birth will not work, even if the woman knows exactly when the conception occurred. According to the established standards, the gestation period lasts exactly 40 weeks, however, rarely does any woman give birth in the DA. And the point is not only that in most situations, the estimated date of birth is determined erroneously.

The duration of the intrauterine finding of the child depends on many factors:

  • the length of the woman’s menstrual cycle;
  • the moment when a mature egg leaves the ovary;
  • the day when the female and male sex gametes merged;
  • the presence of burdened heredity in at least one of the parents;
  • endocrine and hormonal changes in the body of the expectant mother;
  • woman’s age.

In addition to the physiological characteristics of the course of pregnancy, various pathological conditions that occur during gestation can also influence the period when a baby is born. Among them, polyhydramnios or oligohydramnios, early toxicosis and gestosis, increased pressure in the expectant mother, and the presence of a disease such as diabetes mellitus are most common.

When at the next scheduled appointment the obstetrician-gynecologist calls you the day of PDD, then this information does not mean the exact date when the baby is born, but the approximate date when the birth occurs.

It is important to understand that the period from 37 to 42 weeks is considered the normal period for the birth of a child, and questions about the stimulation of childbirth in the normal course of pregnancy are raised after 42 weeks, when the fetus is already considered to be postponed.

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