By the fifth month of pregnancy fine hair called lanugo covers the body the foetus. Lanugo disappears late in pregnancy or shortly after birth. Hair also appears on the head. From the ninth week of pregnancy until birth, the developing baby is called a foetus. In the first three months of this period, the foetus increases rapidly in length. It grows about 5 cm (2 inches) in each of these months. In the later months of pregnancy, the most striking change in the foetus is in its weight. Most foetuses gain about 700 grams (25 ounces) in both the eighth and of ninth months of pregnancy. The mother can feel movements the foetus by the fifth month of pregnancy. The eyelids open by the 26th week of pregnancy. By the 28th week, the fingernails and toenails are well developed. Until the 30th week, the foetus appears reddish and transparent because of the thinness of its skin and a lack of fat beneath the skin. In the last six to eight weeks before birth, fat develops rapidly and the foetus m becomes smooth and plum