Methods for determining gestational age

Determining the most accurate gestational age is important, both women and obstetricians. This is due to three reasons. First of all, according to gestational doctor will be able to observe the development of the fetus and the right time to determine its intrauterine growth retardation. The second, on the gestational age calculated by the date of maternity leave Maternity leave: how to survive it . And finally, the gestational age helps to clarify the expected date of birth.

Normally, pregnancy lasts 280 days or 10 obstetric months, plus or minus 14 days. Why is determined by the estimated rather than the exact date of birth? Just every pregnancy proceeds differently, even in the same woman, so that no doctor will be able to give an exact date of birth.

Official, precision, medical methods for determining the pregnancy a few:

• by date of last menstrual period;
• by date of ovulation;
• by ultrasound;
• the first appearance in the antenatal clinic;
• height standing uterus;
• in the first perturbations.

Determination of gestational age on the date of the last menstrual period

Determination of gestational age by this method is simple and quite effective. To do this, make small payments from the month of last menstrual period and take three months to add seven days. For example, last month was 07/08/09. Consuming three - obtained in May (the fifth month) and added 7 days - out of 14 numbers. That is, the term of delivery will be - 14/05/10. From these data, we can already calculate the current and duration of pregnancy, taking delivery period for 40 weeks, or 280 days.

Determination of gestational age on the date of ovulation

This calculation is only suitable for women who know their day of ovulation (and it will be the day of conception). Women who regularly measured rectal temperature or held ultrasound dynamics (after ovulation stimulation) can know the date of ovulation. To this day, enough to add 280 to get the expected date of birth.

Determination of gestational age by ultrasound

In this case, it all depends on the time when it was produced by the first ultrasound. The earlier ultrasound done, the more accurate term of pregnancy. For example, ultrasound before 12 weeks helps to determine the time to within 1-3 days. US spent in the period up to 28 weeks ot13 precisely with an accuracy of up to seven days. A later ultrasound does not provide any data on pregnancy, since in this period can be observed as well as intrauterine growth retardation, and its overweight.

Determination of gestational age at the first appearance in the antenatal clinic

This method is only good for early turnout (12 weeks) of pregnancy to the doctor. In this case, the determination of pregnancy by palpation performed (by touch) by vaginal examination. Thus, in the period of 5-6 weeks, the uterus is the size of a hen's egg, in a period of 8 weeks its dimensions are similar to the size of a fist or a female goose egg, a period of 10 weeks in size can be compared with a man's fist, and in a period of 12 weeks will be the size of the uterus the head of the newborn.

Determination of gestational age on the first fetal movements

Earlier gestational age was considered the first baby move, although it begins to move as early as eight weeks. That is not determined by the first stirring, and the first sensation of fetal movements of the pregnant woman. In the first stirring primigravidas should take place in a period of 20 weeks, while in multiparous period of 18 weeks. Although it is known that many women feel the first stirring and at 15-16 weeks, and some do not feel it at all up to 22 weeks. It is related to physical activity of the child, its location in the uterus, and the sensitivity of the walls of the uterus.

Determination of gestational height fundal

This method of determining gestational age is important after 22 weeks. The average height of standing uterus (the distance from the upper edge of the pubic symphysis to the upper end of the uterus) must comply with the pregnancy. For example, in a period of 29 weeks height fundus equals 29 cm. This method is also relative and depends on the constitutional features (excess fat or thinness) and on the position of the fetus in the uterus (in transverse position height is lower), the quantity of water ( polyhydramnios or oligohydramnios), the number of births (or elastic stretched abdominal wall).

Anna Sozinova

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