Fifteen week old foetus. Computer graphic of a human foetus in side view, 15 weeks (3.5 months) old. At this age the foetus appears completely human with lips, eyelids and external ears. Fingers and toes are formed, and the arms, legs and face appear thin due to a lack of subcutaneous fat. At this time the foetus is covered in fine hair and eyebrows and head hair are forming. The crown-rump length (sitting height) of the foetus is about 13-14cm and its weight 180-200g. The head is proportionately large, although the body is elongating at this stage. The sex of the foetus is well established, although not seen here.