Exercise during pregnancy is not only healthy for mom, but also for baby. The U.S. Department of Health and Human Services recommends that pregnant women get at least 150 minutes of moderate-intensity aerobic activity per week. The American College of Obstetrics and Gynecology also recommends that:
- A pregnant woman should be evaluated by her doctor to rule out possible reasons not to exercise.
- If doctor-approved for exercise, a pregnant woman should engage in regular, moderate-intensity physical activity to continue getting the same associated health benefits during pregnancy as she did before pregnancy.
While these are good foundations for exercise during pregnancy, there are still important questions that have yet to be answered, such as: What about different types of exercise such as weightlifting and interval training? What exactly are “moderate” and “vigorous” exercise for pregnant women? Recently, the issue of lifting heavy objects while pregnant has gained some attention in the media and fitness communities. When it comes to heavy lifting, the research verdict is still out. The guidelines for lifting and pregnancy are often taken from occupational studies, where women have to lift objects as part of their jobs, not necessarily to improve their fitness. In addition, organized studies on pregnant women are ethically complicated, so determining the effects of certain types of exercise can be difficult.
- Exercise and physical activity are important during pregnancy, for the health of the mother and the baby. However, the guidelines are unclear on intensities and types of exercises that are safe.
- Guidelines for lifting during pregnancy are often derived from occupational studies and may not be applicable to lifting for exercise.
- Pregnant women need to consult with their doctor before beginning an exercise program, or about the safety and limitations to their current exercise program.
What We Know
There are some things about exercise and pregnancy that we know for certain. First, pregnant women should avoid being supine (on their backs) for extended periods of time. For example, sit-ups or supine bench presses are not safe and should be avoided because of the risk of cutting off blood flow to the fetus. Also, any activity that increases the risk of falling, specifically on the belly, should also be limited. Examples include skiing, box jumps, and contact sports.
There is research both to support and refute the safety of heavy lifting on fetal health. Some studies that have found that lifting heavy weight increases the risk of pre-term birth. These risks seem to affect women who are less than 12 weeks pregnant and lift heavy loads multiple times per day. However, other studies suggest that lifting heavy weights in the later stages of pregnancy does not seem to have negative effects on the baby, at least in those women who have experience with weight training prior to being pregnant.
It’s also important to remember that the physical changes that come with pregnancy can affect both the ability to do exercises and how various forms of exercise affect a woman’s body. For example, pregnancy changes a women’s overall body mass and center of mass, as well as spinal curvature, which may cause spinal instability, along with changes in balance and increase in flexibility around joints. These factors and others may affect the way a pregnant woman performs exercises, even ones she may have engaged in prior to pregnancy.
Most of the data about lifting during pregnancy come from studies of occupational lifting. But these conditions are very different from those of a gym for fitness center where the aim of lifting weights is to improve muscular fitness. As a result, it’s difficult to conclude that fitness-related heavy weightlifting will have the same effects as work-related heavy weightlifting. And that also means that the specific concerns and recommendations for occupational lifting may not translate for recreational lifting.
Exercise during pregnancy is healthy for both mother and baby. More often than not, women don’t get enough exercise during this time; but for highly fit, even elite, athletes, the research is limited on “how much is too much” when it comes to exercise during pregnancy. More research is needed in the specific area of heavy weightlifting for fitness during pregnancy, not just for job-related activities. This is especially important for women in the military, whose job demands lead them to participate in weightlifting exercise to keep up their fitness.
Each service has its own guidelines and policies regarding exercise and care for pregnant service members. Pregnant women should avoid the high-risk exercises and postures discussed above. Women who have a history of pre-term labor, cervical incompetency, and other conditions their doctors identify as high risk should work closely with their healthcare professional in terms of what exercises are appropriate. Be sure to consult your doctor about the kinds of exercises that are right for you and your baby before you begin any exercise program.