fetus at 16 weeks of regnancy Your baby can smile! At 13-14 weeks the baby's muscles around the mouth have formed enough to enable a smile. The baby's liver has begun to secrete bile and the pancreas is producing insulin. The baby at 13 weeks will weigh between 13 and 20 grams. The placenta is fully functioning now and will have to produce hormones to sustain the pregnancy (progeterone) and its all systems go! Between 15 and 16 weeks The skin is very thin and you can see the blood vessels clearly underneath. The scalp hair pattern is developing while fine hair (called lanugo) covers the baby's body. The baby is approximately 12-14 cm (3.7 to 4.1 inches) and weighs about 50 grams by the end of week 15 By 13, morning sickness for some women may have begun to ease and they may even find their clothes getting a little tight although it will be a few more weeks before a prominent bump appears. At 16 weeks The top of the womb can be felt between the pubic bone and naval. A heartbeat can be detected through a midwifes pinnard or sonicaid, which is an electronic listening device