Active Voice: More Maternal Physical Activity May Lead to Leaner Pre-Adolescent Children
by James M. Pivarnik, Ph.D., FACSM

Active Voice is a column by ACSM experts in science, medicine and allied health. The viewpoints expressed do not necessarily reflect positions or policies of ACSM. NOTE: The research discussed in the following feature was presented at the 57th ACSM Annual Meeting June 2-5, 2010. Lanay Mudd and Sarah Bartholomew were co-authors on this presentation.

James M. Pivarnik, Ph.D., FACSM, is a professor in the Departments of Kinesiology and Epidemiology at Michigan State University. He directs the Center for Physical Activity and Health and is the University Research Integrity Officer. His research focuses on health aspects of exercise during pregnancy and the postpartum period. Jim is immediate past president of the ACSM and leader of the 2009-2010 ACSM “Exercise is Medicine™ On Campus” initiative.

Erin Kuffel is a doctoral candidate at Michigan State University. She will obtain her Ph.D. in Kinesiology with a specialization in exercise physiology in Spring 2011. Her research interests are the effects of physical activity during pregnancy on both the mother and child. For this particular project, Erin played an integral part in data collection, analysis, and interpretation. She is a student member of ACSM and presented part of this research at the 57th Annual Meeting of the American College of Sports Medicine.

The prevalence of childhood overweight and obesity is approximately 32 percent and behavior modifications are necessary to curb this epidemic. Oftentimes, child physical activity (PA) levels and diet are examined, as they are obviously the keys to energy balance. There is some evidence that the in-utero environment, including maternal physical activity during pregnancy, may also be involved with energy balance. However, this behavior has not been well-studied with respect to a child's body size. Our line of research on maternal physical activity during pregnancy on child health includes the effect on child’s body size at age 8-10 years. We found that a mother’s current aerobic fitness was inversely related to her child’s body mass index (BMI), percent fatness, and waist circumference at age 8-10 years. We hypothesized that the mother’s current aerobic fitness acted as a surrogate of pregnancy fitness level and possibly enhanced the in-utero environment. Thus, our study participants who were more aerobically fit currently were also fitter during pregnancy and currently have children with lower body size and fatness. This finding supports the notion that fitter women provide an in-utero environment that supports growth less likely to predispose their infant to high body fatness.

We also found that these mothers recalled higher levels of PA during their second and third trimesters, which were related to lower child body size measurements at 8-10 years of age. The second and third trimester is when a majority of fetal growth occurs and therefore, higher levels of PA by the mother later in pregnancy may beneficially alter the in-utero environment. Overall, our results support the works of other researchers who found lighter and leaner infants at ages 1 and 5 years among women who exercised throughout pregnancy, by extending the findings to older children (8-10 years).

There are many reasons why women should become or remain physically active during pregnancy, with most research focusing on maternal effects. Our preliminary findings provide support for an additional health benefit from maternal PA, with the recipient being the child. Specifically, a mother’s PA levels during pregnancy could have a lasting, beneficial effect on her child’s body size. Therefore, promotion of PA during pregnancy, especially during the second and third trimesters, is imperative for not only a woman's health, but the health of her child as well.

Editor’s note: See Sports Medicine & Exercise Science Headlines for Tips for Pregnant Runners.