Pregnancy Stages

Pregnancy Stages are divided into three 3-month stages, called trimesters. During each trimester, different things happen to both the woman's body and the growing baby. Changes occur in the size and shape of the uterus, abdomen, and breasts during pregnancy.

First trimester

During the first trimester, the uterus begins to stretch gently to make room for the growing embryo. The baby grows to a length of about 3 inches and a weight of I ounce by the end of the third month. It is during this time that the vital organs— heart, lungs, intestines, brain, eyes, ears, and skeleton—are formed.

Second Trimester

The baby grows to a length of about 14 inches and a weight of 2 pounds during the second trimester. Movements of the fetus, called "quickening," happen at around 20 weeks. The doctor will be able to hear the baby's heartbeat. Bones are growing, arm and leg joints are forming, and the baby's teeth are well started.

Third Trimester

During the final trimester, the baby's tissues and organs mature, and strength and weight are gained. The baby also starts kicking and moving about. The uterus moves higher in the abdomen until about the middle of the last month. The baby's head then begins to drop into the pelvis in preparation for delivery.