Should a woman exert her body when there’s another body growing inside of it? My gut reaction is that it seems risky—maybe that’s just because TV has given me an image of pregnancy as a time of bedrest and ice-cream eating, and very little exertion. And pregnant women are often told about the importance of rest.
Previously, doctors thought that exercise could lead to preterm birth, because when you work out, you release the hormone norepinephrine, which could cause contractions. Starting in 1985, The New York Times reports, doctors began to cautiously recommend light exercise, and today, moderate exercise is thought to be safe. And a new meta-analysis published in the American Journal of Obstetrics & Gynecology adds to the evidence in favor of pregnant gym time. Researchers reviewed the randomized clinical trials that have been done on a total of 2,059 women who either did aerobic exercise during their pregnancy or didn’t. It concluded that not only was exercise not associated with preterm birth, it was associated with a lot of good outcomes.
Exercise was linked to a lower risk of gestational diabetes (a 2.4 percent risk compared to 5.9 percent in the control group) as well as a lower risk of hypertension (1.9 percent compared to 5.1 percent risk). The women who worked out were also significantly more likely to give birth vaginally than to have a C-section: 73.6 percent of exercising women had vaginal deliveries, while 67.5 percent of non-exercising women did.
The rate of C-sections has been rising steadily in America since the 1960s, and only 38 percent of them are medically necessary, as Sarah Yager reported in The Atlantic in 2014. C-sections are expensive, and bring risks of complications like blood clots, infection, and the potential for placental problems with future pregnancies, as well as risks for the baby, who is more likely to become obese, to have allergies, asthma, and type 1 diabetes. If some swimming or yoga can increase a woman’s chances of natural birth, that’s good news for the mother and child both.
Ultimately, the study found support for “at least 150 minutes of moderate-intensity activity per week,” which is also the amount recommended by the American College of Obstetricians and Gynecologists.
All of this is for uncomplicated pregnancies with only one fetus. Having twins or triplets, or having complications like high blood pressure or anemia may still be reasons for doctors to recommend that women stay relatively sedentary while pregnant. But this research shows that an average, healthy pregnancy can also be an active one.