Back Pregnancy A pregnancy is divided into three phases, called trimesters. Each trimester has its own significant milestones. Listed in the directory below, you will find additional information regarding the three phases of pregnancy, for which we have provided a brief overview. Pregnancy Overview Anatomy: Fetus in Utero The First Trimester (0 - 12 Weeks) The Second Trimester (12 - 24 Weeks) The Third Trimester (24 - 40 Weeks) The Pregnant Mother Hormones During Pregnancy Weight Gain During Pregnancy Nutrition During Pregnancy Exercise During Pregnancy Work and Pregnancy Sex During Pregnancy Sleeping During Pregnancy Multiple Pregnancy Overview of Multiple Pregnancy Symptoms and Diagnosis of Multiple Pregnancy Complications of Multiple Pregnancy Care and Management of Multiple Pregnancy Newborn Multiples