A lot of what you can and can't do physically during pregnancy comes down to common sense like no scuba or contact sports but some things aren't so obvious.
Click here to read our main story on exercising for expectant mothers.
Pay attention to changes in balance and mobility. Every day is different during pregnancy.
Drink plenty of water to avoid dehydration and overheating.
Work out in a well-ventilated space.
Be sure you can carry on a conversation comfortably during the workout.
Consume the appropriate extra calories for pregnancy and exercise to ensure healthy baby growth. The basic guide-line is 100-300 extra calories a day.
Exercise until you're fatigued (not exhausted).
Exercise in extreme heat or humidity or when suffering from a fever.
Lie on your back after the first trimester.
Stand at attention for long periods. The Army, for example, exempts troops from standing at attention or at parade rest for longer than 5 minutes upon reaching 20 weeks of pregnancy.
Service-specific rules on pregnancy and PT:
Army: Pregnant women are exempt from standard PT training and testing. A Pregnancy Postpartum Physical Training program provides appropriate exercise along with weekly classes on nutrition and caring for a newborn, with the ultimate goal of an easy transition back to unit PT and a successful six-month-postpartum PT test.
Navy/Marine Corps: Sailors and Marines are exempt from their service's physical fitness program during pregnancy and up to six months following delivery. Pregnant troops are exempt from standing at attention longer than 15 minutes.
Air Force: Women are taken off mobility status until four months postpartum.
When to stop
Call your doctor if you experience:
Dizziness or faintness.
Increased shortness of breath.
Calf pain or swelling.
Decreased fetal movement.
Bleeding or fluid.
Source: American Council of Obstetricians and Gynecologists.