A pregnancy is divided into three phases, called trimesters. Each trimester has its own significant milestones. The first trimester is the most fragile period, during which all major organs and systems are formed. Most birth defects and miscarriages occur during the first trimester. During the second and third trimester, the fetus is fully formed and grows and matures rapidly. The trimesters are divided as follows:
first trimester: 0 - 12 weeks
second trimester: 12 - 24 weeks
third trimester: 24 - 40 weeks
(However, some authorities use the 42 weeks method divided by 3 trimesters with the 1st trimester, 0 - 13 weeks; the 2nd trimester, 14 - 28 weeks; and the 3rd trimester, 29 - 42 weeks.)
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