The gestational age is determined internationally based on the weeks and days that have elapsed since the first day of the last period (LMP). It is important to emphasize that the calculation of gestational age based on the month is no longer used in medical practice. The duration of pregnancy from the day of conception to the estimated date of delivery is approximately 40 weeks (280 days). It is estimated that 85% of deliveries will take place one week before or after this date. During the first and second weeks of pregnancy there is actually no pregnancy, but the maternal body prepares for the fertilization of the egg and the implantation of the fetus in the womb.
Pregnancy trimesters
Another more general way of dividing pregnancy is in three trimesters, in which different important events occur:
- In the 1st trimester (up to13 weeks) the various organs of the fetus are formed (period of organogenesis).
- In the 2nd trimester (from 14 to 27 weeks) the good condition and anatomical details of the fetus are checked with the anomaly scan.
- In the 3rd trimester (from the 28 to 40 weeks) the fetus develops, gains weight and prepares for childbirth.
