When your mom was pregnant with you, chances are she wasn’t running, pedaling a stationary bike or doing ball squats. Back then, doctors worried that exercise might harm the growing baby and discouraged pregnant women from breaking a sweat.
But the medical establishment has done a 180. In a development that might surprise your mom’s OB-GYN, researchers are discovering that prenatal inactivity—not exercise—is what puts moms-to-be and their babies at risk. “For low-risk pregnancies, prenatal exercise is absolutely safe. There’s no question about that anymore,” says Michelle Mottola, Ph.D., director of the exercise and pregnancy lab at the University of Western Ontario in Canada. “If mom is not doing any physical activity whatsoever, there’s this huge potential disease risk for her and also for the baby.”
(If your pregnancy is high-risk—for example, you are carrying twins—consult your doctor about how much exercise is appropriate.)
Couch potatoes are at risk: Pregnant women who stay sedentary are more prone to excessive weight gain (which leads to higher Cesarean section rates), pregnancy-induced high blood pressure (which can lead to preeclampsia) and gestational diabetes (high blood sugar during pregnancy). Scientists don’t exactly know why, but these conditions appear to alter the uterine environment in a way that “programs” the babies to carry a higher risk for obesity and diabetes years down the line, Mottola says.
The long-term risks of prenatal inactivity apply to you, too. Women who gain excess weight during pregnancy tend to hang on to those pounds long after pregnancy, increasing their disease and obesity risks, and those who develop gestational diabetes have up to a 60 percent chance of developing type II diabetes within four years, according to Mottola.
Exercise leads to long-term benefits: Exercise can dramatically alter this picture, even for obese women who led sedentary lives before conceiving. “In the past, we used to tell obese women: Don’t move, don’t breathe,” says Raul Artal, M.D., professor and chairman of the department of obstetrics, gynecology and women’s health at Saint Louis University School of Medicine. “But now we have a lot of evidence to show that obese women should exercise during pregnancy.”
Artal’s own published research shows that obese women with gestational diabetes who exercise in addition to controlling their calories gain less weight and deliver leaner babies than those who simply watch their calories. It’s not just overweight women who benefit long-term from prenatal exercise. Even highly fit women who work out during pregnancy appear to be fitter and healthier two decades later than fit women who temporarily quit exercising while pregnant.
Consider a 2008 study by James Clapp III, M.D., director of obstetrical research at MetroHealth Medical Center in Cleveland. Clapp, a pioneer in prenatal exercise research, checked in with 39 women 18 to 20 years after he had initially studied them. Those who’d stuck with exercise throughout pregnancy had gained just 7 1∕2 pounds in the two decades since, compared with nearly 22 pounds for those who quit working out while pregnant but resumed afterward. At age 48, the continuous exercisers were still working out at 82 percent of their prepregnancy levels, compared with 52 percent for the women who took a hiatus. Additionally, the exercisers’ cholesterol levels and resting heart rates were significantly lower.
Why the difference? As Clapp notes in his study, “It is impossible to separate the long-term effects of exercise during pregnancy from those of exercise afterward.” Clapp is conducting further research to answer this question. While researchers continue to study the long-term benefits of prenatal exercise, the immediate benefits are proven: less back pain, more energy and a better body image.
“Even when pregnant women come in to our lab not feeling great, exercising makes them feel invigorated,” says Danielle Symons Downs, Ph.D., an associate professor of kinesiology and obstetrics and gynecology at Pennsylvania State University. “They feel less stressed, more fit and toned and better about their shape.”