Pregnancy and birth are two of the most important events you will experience in your life. Both deserve careful and thoughtful preparation. Learning as much as possible about pregnancy, birth and parenthood will help you be more relaxed and comfortable with all of the changes in your body and your life. Attending childbirth classes, having regular physician appointments, reading books, talking to others, and asking lots of questions will help you prepare for the birth of your baby.

Pregnancy is measured in trimesters from the first day of your last menstrual period (LMP), totaling 40 weeks. The first trimester of pregnancy ends 13 weeks, or about 3 months, after the start of your LMP.:

First Trimester (Weeks 1-13) -- You can expect changes in your physical and emotional states during your pregnancy. You may experience nausea, frequent urination, breast and nipple tenderness, fatigue, bloating and constipation.

Second Trimester (Weeks 14-26) -- The fetus is growing rapidly. At the beginning of the second trimester, the fetus is about six inches long. By the end of month six, the fetus resembles a small infant, except for its reddish, wrinkled skin. It will be 12 inches long at the end of the second trimester.

Third Trimester (Weeks 26-40) -- The baby gains the most weight in the last 13 weeks of pregnancy. Most of the organs are developed at the end of eight months. Tremendous brain growth occurs. At the beginning of ninth month, the baby settles down lower in the pelvis in preparation for labor and birth.

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