In a physiological course, this process lasts ten obstetric months. Another name for obstetric months is lunar months. Such a month lasts 28 days. In everyday life it is customary to say that pregnancy lasts nine months. How is that right? When they say that pregnancy lasts nine months, they mean calendar months of 30-31 days. If we discard this “tail” of two or three days from each month, then just one more lunar month of 28 days will be added.
So that no one gets confused about months, it is much more convenient to consider the duration of the current pregnancy in weeks. A normal pregnancy lasts forty weeks. By the number of days, the result is 280. Of course, it does not always happen that a child is born exactly on the 280th day. If the baby was born at a full 37 weeks, then it is considered full-term. If the baby was born at 42 weeks or more, then it is considered post-term.
Thus, a full-term pregnancy lasts from 37 weeks 0 days to 41 weeks 6 days. A baby born between 22 weeks and 36 weeks 6 days is considered premature. If it turns out this way, the pregnancy is interrupted before 22 weeks, then the resulting fetus is considered a miscarriage.