21 Weeks

At 21 weeks the baby is 25 cm long and weighs about 1/2 a kilo.

The baby's skin is being increasingly covered by vernix. This is a thick, white, greasy cream that protects their skin in their watery environment. Vernix disappears by about 40 weeks, but if the baby is born at 39 weeks or less, you would notice it is still on their skin. The baby's eyelids are still fused shut but the retinas of their eyes are fully developed and they now have distinct eyelashes and eyebrows. The baby's hair follicles are now pigmenting to give them hair colour, looking dark, fair or red!
The baby's blood circulation is completely functional. The umbilical cord system continues to grow and thicken as blood travels with considerable force through the body to nurture the baby. The placenta is now almost equal in size to the baby.

The baby's different organs and systems are maturing. The fetal digestive system is functioning in a simple way and the baby can swallow amniotic fluid. After the baby swallows the amniotic fluid, he is able to absorb water and sugars from the fluid and then the waste is passed as far as the large bowel. The baby swallows the amniotic fluid in order to prepare itself for life outside of the womb. Some babies consume as much as 17 ounces of amniotic fluid in a 24-hour period. The baby already has a high number of red blood cells and the white blood cells are beginning to be produced. Taste buds are being formed on your baby's tongue this week also.