Foetal head presentation. Artwork of a full-term foetus showing normal head (cephalic) presentation within the bones of the pelvis. The pelvis (yellow and pink, centre) is the bony structure at the base of the trunk. It supports the upper half of the body and protects the lower abdominal organs. As childbirth approaches in pregnancy the position of the foetus settles. The foetus and womb drop down together so that the head of the foetus is engaged within the bones of the pelvis as seen here. In the first stages of labour the foetus's head will rotate to enable it to fit through the pelvis during birth.