Full Fetus (Third Trimester) Description
[Continued from above] . . . outgrown its food supply, since the placenta has stopped growing and cannot keep up with the growing need for nourishment. In the last three months, the brain develops very rapidly. In the last two months, a fatty substance called myelin develops. This speeds up the transmission of nervous impulses and forms a sheath around the nerve fibers.
All this time, the baby is gaining more weight. It sheds the down which covers most of the body and the hair on its head may grow very long - long enough, in fact, that the mother may tie a ribbon in a baby's hair right after birth.