Fetal development from 1 to 3 months In the early stages of pregnancy, the relevant organs of the fetus begin to form. For the first few weeks, the fetus is just a cell, but then divides rapidly to form various body parts. The fetal brain, stomach, liver, kidneys and other internal organs will gradually form during this stage. At 3 months, the fetus\’s limbs and fingers also begin to appear. At this time, the fetus is about 1 inch in length and the mother\’s heartbeat can already be heard. The development of the fetus at 4-6 months. As time goes by, the fetus