The baby starts making spontaneous movements at about seven weeks but the mother does not usually feel the baby moving until about 16 weeks. At 11 weeks the baby swallows the amniotic fluid and passes it back into his urine. He can also produce complex facial expressions and even smile. At 18 weeks he is active and energetic and does a lot of muscle-flexing. It can make an impressively hard fist and pucnhes and kicks.