Determination of Due Dates

Contrary to the hopes of many expectant mothers, especially those expecting their first child, it is almost impossible to determine the exact date of birth in each specific case. The date of the upcoming birth is estimated to within a few weeks in one direction or another. Of course, in old manuals you can find schemes for accurately calculating the time of the upcoming birth, but modern medicine recognizes that it is unrealistic to determine the due date down to the day. There are many reasons for this.

Firstly, even if a woman knows exactly the date of sexual intercourse, which became the beginning of pregnancy, this does not mean that she also knows the date of fertilization. Sperm can live in a woman’s body for several hours or even days, maintaining their fertilizing ability.

Secondly, when they try to calculate the onset of pregnancy based on the timing of ovulation, it must be taken into account that ovulation can occur between the 8th and 16th day of the cycle, depending on its duration. This means that fertilization can occur on any day from the 8th to the 18th day of the menstrual cycle, and taking into account the viability of sperm in the woman’s genital tract, another two or three days can be added to the beginning of this period. By the way, it is in this case that conception can occur during menstruation: if menstruation is long, the cycle is short, and sperm have retained their activity for several days and their ability to fertilize.

Finally, the duration of pregnancy is not always exactly 40 weeks - the pregnancy is considered full-term at 37-38 weeks, after which childbirth can occur at any time.

Not to mention the fact that, for example, a multiple pregnancy almost always ends in birth 1-2 weeks earlier than a single pregnancy.

In addition, the time of birth can be influenced by the individual characteristics of the expectant mother: for example, diseases such as hypertension or diabetes mellitus delay the due date.

There are many more reasons why determining the exact day of birth becomes an activity comparable in accuracy to fortune telling on coffee grounds, that is, a coincidence before the date can occur more by chance than by pattern.

American specialists from the Oregon Center for Genetics and Perinatal Medicine, based on several thousand birth histories, determined that the real date of birth in 95% of cases does not coincide with the date that was originally set.

However, it is possible to determine the approximate date of birth, which doctors do with success. Let us repeat once again: we are talking about an approximate date, which in no case can be considered final, so doctors offer a compromise option: determine the week during which the birth should take place.

The expected due date is determined in several ways:

1. By date of last menstruation.

2. By the date of the first fetal movement.

3. By date of first appearance at the antenatal clinic.

4. Based on objective signs (size of the uterus, volume of the abdomen, height of the uterine fundus, size of the fetus).

5. According to ultrasound data.

A combination of several methods is considered the most accurate. However, the due date may shift by 1-2 weeks due to the individual characteristics of the pregnancy. Therefore, it is important to understand the approximate nature of the estimated date and be prepared for the birth within a week before and after the expected date. The child himself determines the moment of birth he needs.