/ / How to calculate the duration of pregnancy

How to calculate the duration of pregnancy

The term of pregnancy can be accurately calculated by conception, by the first movement of the fetus, by the first day of the last menstruation, etc.

By conception

Conception of the child occurs at the time of the confluenceSperm and egg, which should occur in the 1-2 days after ovulation in a woman. Many women learn about ovulation for the following symptoms: thick mucous discharge, tingling in the lower abdomen and around the ovaries, an obvious sexual attraction. Other women use special tests for ovulation for contraceptive purposes to exclude unwanted pregnancies during ovulation days or vice versa, with a view to conception. Some women determine basal temperature to learn about ovulation.

However, even if the day of conception is certain,That is possible in a situation of a single sexual intercourse, doctors put a longer period of about 2 weeks. There is an erroneous opinion that this is due to the fact that the fruit is large, but it is not so. The size of embryos in early terms does not differ. And doctors calculate the obstetric term of gestation, from which they then repulse when determining the date of delivery. In other words, the definition of pregnancy on conception is important and informative for the woman herself, but not for the doctor.


The obstetric period is determined in a different way and withoutAccounting for the day of ovulation. In order to establish this period accurately, the doctor needs information about the first day of the last menstruation, and the duration of bleeding, in general, is not important. It is from the moment of the first day that the pregnancy begins counting. Therefore, it often turns out that the gestation period, determined by you for conception or for ovulation, differs from obstetric for a period of two weeks. Now this should not cause you any surprise.

Date of the first stirring

Usually, in determining the expected date of deliveryThe doctor is guided by the above-described obstetrical gestation period, the indications of ultrasound examinations in the early stages of pregnancy and that is not unimportant, by the date of the first stirring of the fetus. The baby starts to feel primiparous women on the 20th week, re-rousing much earlier - on the 18th week.

Ultrasound examinations

In the absence of pregnancy pathology, the first ultrasoundPerform for 12-14 weeks, although this period is not suitable for the exact determination of the gestational age. Intrauterine development of embryos is the same only during the first weeks after conception. Just in this period the doctor can establish a gestation period of up to 1 day. Ultrasound examines the location of the fetus, palpitation, if any, etc. If the fetus lags behind in development according to the criteria of ultrasound or any deviations are detected, the studies are repeated after 7-10 days. Repeated ultrasound helps to identify a dead pregnancy in the early stages and other abnormalities.

Term of pregnancy based on ultrasound results more accuratelyIs determined on an early basis. Follow-up ultrasound on the 20th and 32nd week is accompanied by a refinement of the gestation period according to the size of the body parts and their proportions. Note that in the second half of pregnancy the fetus develops very individually. The birth of an infant on time with a weight of 2800-4000 is considered the norm.

Visit the gynecologist

The first visit to a gynecologist by a future motherAlways accompanied by an examination that should identify abnormalities and determine the duration of pregnancy, the location of the fetus in the case of an ectopic pregnancy. In the period of 5-6 weeks (delay of menstrual periods for 3-4 weeks), the uterus is increased slightly. In size, it is comparable to a chicken egg, by 8 weeks - with a goose egg, at 10 weeks - with a female fist. At 12-14 weeks, the doctor can accurately determine the length of the uterus when viewed with a centimeter tape.

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