Pregnancy is normally 40 weeks long. It is grouped into three trimesters, with the first trimester considered to be the most critical. During the early stages of pregnancy, you will experience various symptoms that include exhaustion, mood swings, nausea and other physical changes. The latter stages of pregnancy are characterized by symptoms such as difficulty in sleeping, mild contractions, swelling of the feet and heartburn. When the pregnancy reaches 37 weeks the baby is considered full term, with its organs ready to function. When born, babies normally weigh from 6 to 12 pounds and 19 to 21 inches long.