During week 19 your baby’s skin becomes covered with a slippery white, fatty coating called vernix caseosa, or vernix for short. Vernix helps protect the baby's delicate skin, keeping it from becoming chapped or scratched. Under the vernix, fine, down-like hair called lanugo covers your baby’s skin.
Your baby’s kidneys are now developed enough to make urine. The urine is excreted into your amniotic sac, the bag of waters inside your uterus that contains your baby and your amniotic fluid. Unlike your urine, your baby’s urine is completely sterile because he or she is living in a sterile environment. Therefore, when your baby swallows amniotic fluid containing urine, it is not a problem. His or her hearing is now well developed. The baby is probably hearing lots of different sounds, maybe even your conversations. Mom's voice is by far the most prominent in any conversation. If you sing or talk to your baby, it’s reasonable to think he or she might notice. It’s less clear whether your baby is able to recognize particular sounds.
Your baby’s brain continues to develop millions of motor neurons, nerves that help the muscles and brain communicate. As a result, the baby now may make conscious muscle movements, such as sucking a thumb or moving his or her head, as well as involuntary movements. You may or may not be able to feel these movements yet. If you haven’t, you will soon.
You have started to put weight on your bottom, hips, and thighs as well as your abdomen. Tiny veins may start appearing on your lace. These are very small broken blood vessels which are caused by circulation changes. They will disappear after the birth.
The baby is starting to put on weight and its rapid rate of growth has begun to slow down. The milk teeth have developed in the gums and the buds for the permanent teeth are beginning to form. The baby is around 6 inches (15,2 cm) long and weighs about 8.5 ounces (240 grams)