19 week old foetus. View of the face of a 19 week old male foetus sucking his thumb. The foetus is seen within his protective amniotic sac. At this age the foetus appears completely human. Fingers and toes have formed and the skin is covered with a fine hair called lanugo (not clearly seen). The foetus' crown-rump length at 19 weeks is about 18 cm and his body weight is about 400 grams.