Exercise during pregnancy can keep weight gain in check, reduce your risk of gestational diabetes, decrease discomfort, and set you up for an easier labor and delivery. Now, new research shows that breaking a sweat, especially after 29 weeks, has a big benefit for your baby, too.
In a study of 826 mothers and their babies, researchers found that mamas who exercised in their third trimesters gave birth to babies with less body fat, reports the journal Obstetrics & Gynecology. In fact, women who burned the most calories through third-trimester exercise gave birth to babies with 41.1 g less fat mass compared to women who exercised the least.
“Prenatal exercise may reduce the amount of glucose and fats mothers make available to their babies, helping them grow more optimally,” says Dana Dabelea, MD, PhD, associate professor at the University of Colorado School of Public Health, and author of the study. (Read about the downsides to “Big Baby Syndrome” in The Easiest Prenatal Exercise Plan Ever.)
Even if you weren’t active earlier in your pregnancy (thanks, morning sickness), it’s never too late to start moving. The third trimester is when most of your baby’s fat tissues develop, so that’s when exercise may have the biggest payoff in terms of your baby’s body fat, says Dr. Dabelea.
Don’t worry: You don’t need to be a marathon runner to reap the rewards. “Women in the most active group typically had full-time jobs, did other activities at home, and maybe walked, swam, or biked a few minutes each day,” explains Dr. Dabelea. The CDC recommends doing 30 minutes of moderate-intensity physical activity, such as brisk walking, most days of the week throughout your pregnancy.