How to accurately determine the duration of pregnancy
Pregnancy is a long-awaited moment in the life of a woman. From the moment of conception, the future mother already wants to know the date of birth of her baby.
Here everything is not always clear and unambiguous. Here, for example, is one of the questions that I receive daily:
“Tell me, please, I am pregnant, I have to give birth on monthly basis on September 24, by ultrasound at 18 weeks put the deadline for October 16, the second ultrasound at 33 weeks – put on October 11. But when I made out the documents at the maternity hospital, I was sent for another ultrasound, and it showed on September 30th. How can this be and what should I do, go to save now or wait for it? Thanks in advance”.
How to accurately determine the duration of pregnancy?
Different methods are used to determine the gestational age and the date of birth.
Determination of gestational age and date of birth by the date of the last menstruation
Usually the first thing that a gynecologist asks at the reception is the date of the last menstruation.
In obstetrics and gynecology, the cyclical nature and regularity of menstruation is an indicator of a woman’s health.
In order to track the regularity of menstruation, a woman needs to keep her menstrual calendar..
The most common way to determine the date of birth is the method by the date of the last menstruation.
The starting point is taken first day last menstruation. From this day, 40 weeks or 280 days or 9 months of calendar or 10 lunar months are counted – this will be the approximate date of delivery.
Date of birth by this method is also determined according to the formula Negele: From the first day of the last menstruation, it is necessary to count 3 months ago and add 7 days to this date. This will be the date of the intended delivery.
For example, the first day of menstruation was October 1. From this date we count back 3 months (September 1. August 1, July 1 and add 7). It turns out July 8 – estimated date of delivery.
ATTENTION! This is only the estimated date of delivery,
What does it depend on? From many factors. From the course of the pregnancy itself, from the maturity of the child, from the readiness of the mother’s body for childbirth, from diseases afflicting pregnancy.
Determination of the term of delivery by the date of ovulation
Determining the duration of pregnancy and the date of delivery for ovulation is more accurate. From the date of ovulation, consider the past weeks – this will be the gestational age by the date of ovulation.
If you know the day of your ovulation, then add to this date 273-274 days and get the estimated date of birth.
Definition of term of delivery by the date of conception
This is a more accurate way if you know for sure. date of conception or intercourse, especially if he was the only one. From the moment of conception to the moment of delivery 266 days should pass.
Add to the date of conception 266, and you will receive an estimated date of delivery. It will also be approximate
What other ways are there to determine the duration of pregnancy?
Determination of pregnancy by ultrasound
From the moment the fetus is immersed in the uterine cavity, using the ultrasound machine you can already see signs of pregnancy. They are determined by the size of the uterus, by the size of the ovum, by the size of the embryo. In later periods – along the length of the thigh, the length of the shoulder, the size of the head and abdomen of the child, the thickness of the placenta.
There are special tables on which the doctor calculates the timing of pregnancy, comparing the data.
Determination of gestational age by the height of the uterus bottom (WYD)
In later periods, beginning from 14-16 weeks, the uterus emerges from the pelvis and is already palpable over the woman’s womb. The doctor measures the height of the bottom of the uterus with a centimeter tape.
As a rule, WYD in centimeters = gestational age in weeks. For example, WYD = 16cm, so according to WYD, a woman has 16 weeks of pregnancy.
Determination of gestational age on gynecological examination
Examination by a gynecologist is one of the exact methods for determining the duration of pregnancy. Normally, the uterus has a size of 3x4x5 cm. During pregnancy, the uterus increases in size, becomes rounded, soft, and its anterior-posterior size increases.
Establishing the period of pregnancy, the gynecologist focuses on the size of the uterus. They are measured in weeks of pregnancy. For example, the uterus is the size of a newborn’s head – this is 12-13 weeks of pregnancy.
Determination of the term of delivery for the first movement
The stirring of the child begins to feel the primipara woman from the 20th week of pregnancy, and multiplying – from the 18th week.
The doctor will ask you to remember the date of the first movement. From this date, 20 weeks are counted for nulliparians and 22 weeks for multiparums and an approximate date of delivery is given.
Sometimes women begin to feel a stir from earlier periods. For example, from 15 weeks. But in this case, the calculation of the date of delivery will not be very accurate.
In practice, to determine the duration of pregnancy and the date of delivery, the doctor will use ALL these methods.
If there is a discrepancy between the size of the child and the gestational age, this means signs of intrauterine growth retardation and requires special treatment.
Thus, in order to establish the correct gestational age and determine the date of birth, many calculations, measurements, and calculations are required.
Currently, the date of childbirth is very often determined by the doctors themselves or pregnant women when they decide that the pregnancy should be terminated with a cesarean section, but more on that next time.