The third trimester of pregnancy extends from 28 weeks after the last normal period to birth. Childbirth usually occurs between the 38th and 42nd weeks of the pregnancy. During the third trimester, a baby continues to grow larger and the organs mature.

The mother will probably notice increase movement from the baby early in the third trimester. As the baby gets larger during the last 2 months, it may seem like movement is less. This is because there is simply less room to move.

During the third trimester, a baby's weight will go from about 2 pounds to about 7 pounds. The baby will be 13 inches long in the beginning of the third trimester and be around 19 inches at the end of the trimester. By the end of the third trimester, the bones of the skull are becoming hard, but the bones in the limbs are still growing rapidly. As the pregnancy draws to an end, a baby usually moves into a head-down position. This is the best position for the baby to deliver when labor occurs.