Determining the length of pregnancy and the date of delivery

To date, there are many ways to determine the timing of pregnancy and the date of delivery.

How to determine the duration of pregnancy

So, if you make a pregnancy test or visit a gynecologist, you are sure that you are really pregnant, then you can count the gestation period by the date of the last menstruation. Consider the fact that you need to count from the first day of the last menstruation. Pick up a calendar and count how many weeks have passed since the first day of the last menstruation - this will be the period of pregnancy.

How to determine the date of birth according to the last menstruation day

To find out the term of birth, use the formula of NEGEL.From the first day of the last menstruation count 3 months ago and add 7 days.

It is also possible to add 280 days to the first day of the last menstruation, that is, 10 lunar months, which is the date of delivery. When counting, do not forget that one lunar month is 28 days, that is 4 weeks. But more often in obstetrical practice for convenience use the formula of Negel.

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It should be noted that the above method can be used only in women with a regular menstrual cycle. If the cycle is irregular, then errors in the calculations are possible.

Below is a table that will help you quickly calculate the date of expected delivery by the date of the last menstruation.

Determination of the probable date of birth

It is necessary to find the date of the 1st day of the last menstruation in the red line of the table. The figure in the yellow row of the table under the date found indicates a probable day of childbirth.

For example: date of menstruation on January 11, probable day of birth on October 18.The date of menstruation on June 13, the probable date of delivery is March 20.

Determining the gestational age and the date of delivery by the date of ovulation

You can also calculate the gestational age by the date of ovulation. As you know, ovulation occurs in the middle of the menstrual cycle( approximately 12-16 days of the cycle, if counted from the 1st day of menstruation).It is during this period that conception occurs. From this moment the pregnancy is counted down, adding 2 weeks. That is, if ovulation or conception occurred on March 14-15, then the pregnancy period should be counted from March 1-2.

To determine the date of birth by ovulation, it is necessary to subtract 3 months and 7 days from the date of ovulation / conception. Or, you can add 38 weeks to the date of ovulation / conception.

This method is ideal for women who have become pregnant artificially through in vitro fertilization( IVF) or by insemination with partner sperm. Since artificial insemination is performed during the days of ovulation, the woman knows exactly the day of conception and it is easier for her to calculate the pregnancy period and the date of birth more easily and accurately.

Definition by ultrasound

You can also determine the timing of pregnancy and the date of birth according to ultrasound( ultrasound) data. To do this, measurements are made of the fetal size, which corresponds to a certain period of pregnancy. The method is more reliable in the first trimester of pregnancy. In the 2nd and 3rd trimester, errors in determining the exact timing of pregnancy are possible, because each fetus has its own constitutional features. In addition, the mother or fetus may have various pathologies( for example, diabetes maternal or fetal hypotrophy) that will interfere with the normal growth and development of the fetus, or, conversely, contribute to its excessive growth and development.

Other methods for determining the gestational age and the date of delivery

The gynecologist can determine the gestational age according to the examination of the pregnant woman on the chair. When vaginal examination is determined the size of the uterus, which increases gradually during pregnancy.

In later terms, when the uterus is well probed through the abdomen, there is no need to perform a vaginal examination to determine the gestation period. To do this, it is sufficient to measure the centimeter height of the standing of the uterine fundus above the womb and the volume of the abdomen.

It should be noted that in some cases this method is not always reliable. For example, if a pregnant woman has a uterine myoma, the uterus will be larger in size than it should be in the prescribed period. Also, the uterus can be more normal in case of polyhydramnios and in case of multiple pregnancy. And, conversely, with fetal hypotrophy, hypochlorism, undeveloped pregnancies, the size of the uterus will lag behind the prescribed ones.

Let's consider a method of determining the term of pregnancy and childbirth, which is less often used than the above, due to the development of additional research methods. However, this method has its practical value, and serves as a sure sign of the health of the baby.

This is the definition of the gestation period for the first fetal movement. The first wiggling of the fetus will be felt by the first-born mother in the 20-21 week of pregnancy. Repeated people feel the first movement of the fetus, starting from 18-19 weeks of pregnancy.

In order to calculate the date of birth, it is necessary to add 5 lunar months to the date of the first stirring of the fetus in the event that the forthcoming birth is the first. If the birth is repeated, then by the date of the first stirring of the fetus, it is necessary to add 5, 5 lunar months.

And in the end there is a bit of general and useful information regarding the duration of pregnancy.

The average pregnancy lasts 10 lunar months, that is 40 weeks, if you count from the first day of the last period. Most women give birth at 40 weeks.

But it does not always happen like this. Normally, a child can be born between 38 and 42 weeks and will be considered complete and absolutely normal. Therefore, you must first know that the date of birth can not be calculated exactly exactly day in and day out. The doctor can only determine the expected date of delivery, based on anamnestic data, examination data and additional research methods.

Obstetrician-gynecologist, Ph. D.Christina Frambos