Scientists have long known that exercising during pregnancy may be good for expectant mothers and boost their unborn children's heart health and brain activity. But the physical activity could also have some significant lasting effects, new research suggests.
Mice born to mothers that voluntarily exercised during pregnancy grew up to be more willing to work out as adults, the study found. The same may hold true in humans, and the research hints that our propensity to be enthusiastic about fitness might begin before we're even born.
Separate observational studies have found that expectant mothers who are physically active have children with similar tendencies, said Dr. Robert Waterland, associate professor of pediatrics and genetics at the USDA Children’s Nutrition Research Center at Baylor College of Medicine in Houston and a co-author of the study. But more research is needed.
"Controlled randomized studies in humans -- similar to the one we reported in mice -- will be necessary to confirm that our results translate to humans," Waterland told The Huffington Post on Monday.
"If maternal physical activity during pregnancy -- perhaps something as simple as going out for a walk once a day -- actually instills in her baby a lifelong love of being active, this would suggest an extremely straightforward and inexpensive intervention to improve health at the population level," he added.
In other words, encouraging expectant mothers to be more active during their pregnancies might lead to healthier future generations.
For the study, published last month in the FASEB Journal, six female mice were granted access to running wheels before and during their pregnancies while six others were not. The researchers monitored each group's running behavior, body weight, body composition, food intake, energy expenditure and overall physical activity.
Once the mice gave birth to their litters -- which each had about eight pups -- the researchers analyzed the offsprings' behavior throughout their lives and into adulthood.
Adolescent mice born to mothers that had exercised during pregnancy became more active themselves, running more miles on wheels than the other mice and moving around their cages more frequently, The New York Times reported.
"The one thing I was surprised about was the magnitude of the effect we found," Waterland told HuffPost. "In adulthood, the offspring of mothers that exercised during pregnancy were themselves about 50 percent more active than genetically identical adult mice whose mothers had not used a running wheel before and during pregnancy."
The researchers concluded that a mother's exercise habits during pregnancy may have a long-term effect on her offspring’s tendency to be physically active.
The findings, however, contradict a separate 2015 study led by Dr. Scott Kelly, an assistant professor of zoology at Ohio Wesleyan University. That research was conducted on a different strain of mice and found that maternal exercise had no impact on offspring exercise.
"Sometimes contradictory results can be looked at as a negative, but I think, in this case, it can be a great opportunity to spark further research," Kelly told HuffPost.
"It certainly is a topic that's interesting to study," he said. "We know the propensity to engage in exercise is heritable behavior but what we looked at, and what this study looked at, is what happens if you grant exercise to one group and don't grant exercise to another group."
Next, Waterland's research team aims to investigate why there may be this link between maternal exercise and a child's affinity for physical activity.
It's possible that the jiggling motion that comes from a mother being physically active could influence fetal brain development, he said. This could lead to optimal development of the part of the brain that's linked to physical movement and behavior.
As scientists aim to unravel the mysterious effects of maternal exercise, the American College of Obstetricians and Gynecologists and many other experts stand firm in recommending that women with uncomplicated pregnancies engage in daily moderate workouts before, during and after pregnancy -- for their own benefit, as well as that of their children.
"I think our results offer a very positive message," Waterland said in a statement. "If expectant mothers know that exercise is not only good for them but also may offer lifelong benefits for their babies, I think they will be more motivated to get moving."