period of time when a newborn was an fetus
This means that during weeks 1 and 2 of pregnancy, a woman is not yet pregnant. This is when her body is preparing for a baby. A normal gestation lasts anywhere from 37 to 41 weeks. Week 1 - 2. 1  The first week of pregnancy starts with the first day of a woman's menstrual period. 2  She is not yet pregnant.