Does Childhood Obesity Start in Pregnancy?

A new study finds strong evidence that lifestyle habits in pregnancy—lack of exercise, weight gain, smoking and drinking—could be contributing to childhood obesity.

Does Childhood Obesity Start in Pregnancy? Halfpoint/Shutterstock

Pregnant women can't catch a break—literally. A new study is adding to a larger body of knowledge that draws a strong connection between lack of exercise during pregnancy, excessive maternal weight gain and obesity in future generations. This latest research—part of a collaboration between the University of Texas Medical Branch at Galveston and Harokopio University in Greece—studied pregnancy weight gain, prenatal exercise, cigarette and alcohol consumption in mothers of 5,000 randomly selected children, as well as the body mass index (BMI) of each child at eight years old.

Related: Pregnancy Weight and Obesity: A Domino Effect

Researchers found that moderate exercise in pregnant women was strongly associated with their children having a lower risk of being overweight or obese as a child. Additionally, maternal weight gain beyond the recommended range seemed to predispose the offspring to gain weight. A mere 2.2lbs increase in gestational weight gain correlated with offspring being 1.014 times more likely to be obese or overweight by their eighth birthday. (The study also indicates that maternal smoking has a detrimental effect on future children's BMI, presumably due to the effect nicotine has on the hypothalamus, which regulates appetite.)

Weight vs. exercise: Which matters most?

According to the study, a widespread sedentary lifestyle and the current obesity epidemic seem to "co-exist [and] act synergistically." So does being inactive while pregnant put your child at risk by itself, even if you don't gain too much weight?

"It's not easy to separate those things," says study author Labros Sidossis, Ph.D., professor of Internal Medicine and Surgery at UTMB. "But it looks like all three factors [exercise, weight gain, and smoking] are independently associated. Even if one is present, and not the others it can still have an effect."

Unfortunately, 64.5% of the women in the study had never exercised during pregnancy and only 16.7% achieved moderate exercise, while a mere 1.8% exercised daily. This goes against current standards, which suggest that healthy pregnant women achieve 150 minutes of moderate exercise each week, according to the American College of Sports Medicine and the American College of Obstetrics and Gynecology.

Exercise common sense

"Pregnancy doesn't affect how active you should be," Sidossis says. "If a woman was an athlete [like] a long-distance runner before she became pregnant, she can probably train through the seventh month of pregnancy, assuming everything is safe with the pregnancy itself. It's important that women continue their active lifestyles, and increase their physical activity levels if they're sedentary."

As far as working out goes, Sidossis recommends walking, swimming, and the stationary bike, as long as you have the OK from your doctor and use common sense. Basically anything that doesn't predispose you to falling is probably a safe bet.

While women should strive to be active and stay within the recommended weight gain limits, they shouldn't obsess over it. "Eat well. Get rest. Exercise in moderation," Sidossis says. "And just enjoy this period of your life."

Related: Weight Gain During Pregnancy: How Much is Too Much?