This is the middle third of pregnancy and it is now considered 'safe' to share your news with everyone that you're pregnant. When you reach this stage the risk of miscarriage is much less likely than in the first three months.
By week 13 your baby is fully formed and throughout the remainder of the pregnancy he will grow and his vital organs will mature to make him capable of independent life. By week14 your midwife should be able to hear your baby's heartbeat using a sonicaid, though some midwives and doctors prefer to wait another few weeks to avoid disappointment and panic if it is too difficult to find, your baby is still only about 10cm long and is moving around quite a bit. During week 16 fine hair begins to grow all over the baby's body, this is called lanugo, the eyebrows and eyelashes also start to grow. Your baby's movements are vigorous and you may start to feel them although most women don't for another few weeks in a first pregnancy. As his eyes and ears continue to develop your baby is now aware of sound and light.
By week 20 your baby is about 25cm long and weighs about 12oz. His teeth are forming in his gums and hair is beginning to grow on his head. As his muscles develop his movements increase and become more vigorous, so much so that you should now be able to feel them.
Your baby is continuing to grow and mature at a rapid pace. By week 24 he is about 33cm long and is now considered legally viable - meaning that if he was born now he is capable of sustaining independent life with special care. Although he has the proportions of a newborn he is still very thin and hasn't yet laid down fat stores.
By week 28 your baby's chance of survival, if born early, has increased to 80%. He is beginning to accumulate fat stores and his lungs are becoming more mature. His body is covered in vernix, a thick greasy substance that helps protect the skin from becoming soggy while immersed in the amniotic fluid. He now weighs about 2lbs and is about 35cm long.