Women who do exercise while they're pregnant have slimmer babies, new research from New Zealand shows. Because babies born to moms who didn't exercise had higher than average weights, exercise could have helped "control" the weights of the exercisers' babies.
The team randomly allotted 84 women pregnant with their first baby to up to 5, 40 minute sessions on an exercise bike at home each week or to a no-exercise group, beginning at 20 weeks of pregnancy through delivery.
While there were no differences in the women's body mass index (BMI) or weight, the women who exercised were healthier than those who didn't. The babies born to the exercisers were about 140 grams (5 ounces) lesser than the control groups, even if their average length was the same, leading to a lower BMI.
The researchers had concluded that exercise might help keep the women's sensitivity to the blood sugar regulating hormone insulin, which leans to decline in pregnancy. But there was no variation in insulin sensitivity among the exercisers & the non-exercisers.