Exercising during pregnancy has many benefits, though you'll need to make a few changes to your normal exercise routine. Discuss your exercise plans with your doctor or other health care provider early on. The level of exercise recommended will depend, in part, on your level of pre-pregnancy fitness.

What Are the Benefits of Exercising During Pregnancy?

Exercise is a big plus for both you and your baby (if problems don't limit your ability to exercise). It can help you:

• Feel better. Exercise can increase your sense of control and boost your energy level. Not only does it make you feel better by releasing endorphins (naturally occurring chemicals in the brain), appropriate exercise can:
  
  • relieve backaches and improve your posture by strengthening and toning muscles in your back, butt, and thighs
  • reduce constipation by accelerating movement in your intestines
  • prevent wear and tear on your joints (which become loosened during pregnancy due to normal hormonal changes) by activating the lubricating fluid in your joints
  • help you sleep better by relieving the stress and anxiety that might make you restless at night
• Prepare you and your body for birth. Strong muscles and a fit heart can greatly ease labor and delivery. Gaining control over your breathing can help you manage pain. And if you have a long labor, increased endurance can be a real help.
• Regain your pre-pregnancy body more quickly. If you exercised before your pregnancy, you'll gain less fat weight if you continue to exercise now. But don't expect or try to lose weight by exercising while you're pregnant. In general, the goal is to maintain your fitness level during pregnancy.

Exercise also increases the blood flow to your skin, giving you a healthy glow. Some studies have shown that exercise may even lower a woman's risk of complications, like preeclampsia and gestational diabetes.

What's Safe During Pregnancy?

It depends on when you start and whether your pregnancy is complicated. If you exercised regularly before becoming pregnant, continue your program, making changes as needed.

If you weren't fit before your pregnancy, begin slowly and build gradually as you get stronger. The U.S. Department of Health and Human Services recommends at least 150 minutes (2½ hours) of moderate-intensity aerobic activity each week for healthy women who are not already highly active or doing vigorous-intensity activity. For example, you could do this by walking briskly for half an hour each weekday at lunchtime.

“Moderate-intensity” activities are those during which you can still carry on a normal conversation. They can be:

• low-impact: gentle fluid movements that are easy on the joints (like swimming and yoga)
• high-impact: jumping movements that are harder on the joints. Most women with healthy pregnancies can do some high-impact activities (like jogging or aerobics) that stay at a moderate intensity, as these won't increase the risk of problems like low birth weight, pre-term delivery, or early pregnancy loss. High-impact exercise puts a lot of strain on the body and can be uncomfortable during pregnancy, though, so it’s best to slow down if you feel any discomfort.

High-impact exercises feel like a great workout. But low-impact exercise can still increase your heart rate and oxygen intake while helping you avoid sudden or jarring actions that can stress the joints, bones, and muscles.

Before you continue your old exercise routine or begin a new one, talk to your doctor. Discuss any concerns you have and know that you might need to limit your exercise if you have:

• pregnancy-induced high blood pressure (hypertension)
• early contractions
• vaginal bleeding
• premature rupture of your membranes, also known as your water (the fluid in the amniotic sac around the fetus) breaking early

Exercises to Try

You might try dancing, swimming, water aerobics, yoga, Pilates, biking, or walking. Swimming is especially appealing, as it gives you welcome buoyancy (floatability or the feeling of weightlessness). Try for a combination of cardio (aerobic), strength, and flexibility exercises, and avoid bouncing.

Many experts recommend walking. It's easy to vary the pace, add hills, and add distance. If you're just starting, begin with a moderately brisk pace for a mile, 3 days a week. Add a couple of minutes every week, pick up the pace a bit, and eventually add hills to your route. Whether you're a pro or a novice, go slowly for the first 5 minutes to warm up and use the last 5 minutes to cool down.

If you were a runner before your pregnancy, you might be able to continue running now, although you may have to change your routine.

Exercises to Avoid

Most doctors recommend that pregnant women avoid exercises after the first trimester that require them to lie flat on their backs.

Unless your doctor tells you otherwise, it's also best to avoid any activities that include:

• bouncing
• leaping
  
• a sudden change of direction
• a risk of getting hit in the belly

These include contact sports, downhill skiing, skating, gymnastics, and horseback riding because of the risk of injury they pose.

Some doctors say step aerobics workouts are OK if you can lower the height of your step as your pregnancy progresses, but others caution that a changing center of gravity makes falls much more likely. If you do choose to do aerobics, be sure to avoid becoming extremely winded or exercising to the point of exhaustion.

How Can I Get Started?

Talk to your doctor before beginning any exercise program. When you're ready to get going:

• Start gradually. Even 5 minutes a day is a good start if you've been inactive. Add 5 minutes each week until you reach 30 minutes.
• Dress comfortably in loose-fitting clothes and wear a supportive bra to protect your breasts.
• Drink plenty of water to avoid overheating and dehydration.
• Don't exercise if you're sick. 

It also isn't good for your baby if you get overheated. Temperatures higher than 102.6°F (39°C) could cause problems for the baby, especially in the first trimester. So don't overdo exercise on hot days. In hot weather, avoid exercising outside during the hottest part of the day (from about 10 a.m. to 3 p.m.). Instead, exercise in an air-conditioned place or go for a walk in the mall. Also remember that swimming makes it harder for you to notice your body heating up because the water makes you feel cooler.

What Else Should I Know?

Whatever type of exercise you and your doctor decide on, listen to your body. It's common to feel dizzy early in pregnancy, and as the baby grows, your center of gravity changes. So it can be easy to lose your balance, especially in the last trimester.

Your energy level might vary greatly from day to day. And as your baby grows and pushes up on your lungs, you'll be less able to breathe in more air (and the oxygen it contains) when you exercise. If your body says, "Stop!" — stop!

Your body is signaling that it's had enough if you:

• feel very tired
• are dizzy
• have heart palpitations (your heart is pounding in your chest)
• are short of breath
• have pain in your back or pelvis

And if you can't talk while you're exercising, you're working too hard.

When Should I Call the Doctor?

Check with your doctor if you have any of these warning signs during any type of exercise:

• vaginal bleeding
• unusual pain
• dizziness or lightheadedness
• unusual shortness of breath
• racing heartbeat or chest pain
• fluid leaking from your vagina
• uterine contractions