THE DETAILS: In the small study led by New Zealand researchers, about half of the 84 women (average age 30) performed an exercise routine throughout the second half of pregnancy, while the other women did not. The exercising woman participated in at-home, stationary-cycling exercises starting 20 weeks into their pregnancy and continuing throughout. Women were prescribed a maximum of five moderate-intensity, 40-minute cycling sessions per week. Mothers in the exercising group gave birth, on average, to babies 5 ounces lighter than the nonexercising mothers.
WHAT IT MEANS: As long as your obstetrician gives you the green light, moderate aerobic exercise during pregnancy is a great way to boost the health of mother and child. Researchers already know that exercising during a normal pregnancy can help prevent gestational diabetes and improve the endurance fitness of a mother, which can lead to a speedier, less complicated delivery. The more recent findings pointing to a mother’s exercise leading to a more normalized birth weight show that exercising throughout pregnancy can have lasting health benefits for a child, since larger babies are more prone to childhood obesity.
Here are some tips on exercising during pregnancy from a top expert in the field.
• Get the okay. While exercise during a normal pregnancy is certainly beneficial, it’s not for everyone. Certain complications may make it impossible, so it’s very important to work with your doctor and a certified exercise professional specializing in pregnancy to hash out a routine that benefits mother and child, stresses Jaci Van Heest, Ph.D., professor of kinesiology at the University of Connecticut.
• Factor in your fitness level. Of course, it’s best to be fit before even becoming pregnant. But if you’re pregnant and haven’t really exercised beforehand, you still can start an exercise program while pregnant, contrary to popular belief. Your doctor will most likely recommend low-impact exercises like walking.
If you were active before becoming pregnant, your doctor will likely allow you to continue with the exercise, with the exception of cutting back on heavy lifting. Since you are more likely to feel fatigued and you may need more recovery time, you may have to reduce the number of aerobic workout sessions per week to properly recover, Van Heest explains. Depending on your doctor, your recommended heart rate during exercise may be between 140 and 160 beats per minute, so it's important to use a heart-rate monitor to keep it in range.
• Don't force it. As your midsection continues to grow throughout your pregnancy, certain exercises just become uncomfortable or even unsafe. “Your balance changes,” explains Van Heest, who suggests using exercise machines (that you can fit into) instead of free weights during the latter stages of pregnancy, when women become “front-tipsy.”
Starting later in the second trimester, twisting motions also land on the do-not-do list because women are naturally restricted by the extra bulk that’s in the way. But before that point, Van Heest does encourage crunches and other abdominal exercises that target muscles that are involved in delivery. Kegel exercises, which strengthen your pelvic floor muscles, are also a great way to get your body in gear for delivering your baby.