Exercise during pregnancy also benefits your baby. A research study at Case Western Reserve reported that children of moms who exercised during pregnancy had less percent body fat when tested five years later. Also, other research suggests that babies are more alert if mom exercised during her pregnancy.
Your goal during pregnancy is to maintain your level of fitness. Be sure to check with your physician or midwife before starting any exercise program. The American College of Obstetrics and Gynecology sets the guidelines for safe exercise during pregnancy. Here are their recommendations:

*Regular exercise (at least three times a week ) is preferable to intermittent   activity.
*Avoid exercising flat on your back after the first trimester.
*Modify the intensity of your workout by how you feel.
*Drink water before, during, and after your workout.
*Be sure you eat enough; pregnancy requires an extra 300
  calories per day.
*Stop if you experience pain, dizziness, nausea, shortness of
  breath, bleeding, extreme fatigue, or frequent contractions (and contact your   physician).
*Make sure the aerobic component of your workout doesn’t
exceed 20 minutes.
*Be sure to include warm-up, stretching, and cool down exercises.

Some Good Exercise Choices
Low-impact activities are easier on your joints which are more susceptible to injury during pregnancy.

*Walking- make sure you’ve got good walking shoes and a supportive sports   bra. Start out with a five or ten minute walk, and slowly work up to 20   minutes.
*Prenatal Exercise Class- you get the benefit of a monitored
  program plus the group support.
*Prenatal Yoga- a great way to stretch and strengthen your muscles, as well   as relax.

Make sure your program includes modified exercises for your abdominal, and exercises for your pelvic floor. Strong abdominals help you push the baby out during delivery. Strong pelvic floor muscles help support your internal organs. Pregnancy, not to mention labor and delivery, puts stress on these areas.
With the many “don’ts” of pregnancy, exercise is something you’ll be glad you can “do”.