Effects of Physical Activity on Human Pregnancy Energetics: Testing Maternal Metabolic Limits

Daily physical activity is important for health and associated with positive health outcomes during pregnancy. However, few studies have examined the impact of daily physical activity on maternal calorie requirements and gestational weight gain, and recent research suggests that calorie intake and expenditure may be limited during pregnancy. This project examines whether there are upper limits on maternal energy expenditure during pregnancy and considers potential energy tradeoffs between activity level and other physiological tasks, such as fetal growth. Project results can advance fundamental knowledge about human metabolism and physiology during pregnancy and contribute to discussions about the selective pressures that have shaped hominin bipedalism, metabolism, infancy, and life history. The work can also inform public health research and the management of nutrition and exercise during pregnancy. The project supports student training and mentoring in STEM as well as collaborations between anthropologists and clinicians that benefit both clinical and basic research communities. The investigators test Maternal Metabolic Limits hypotheses by measuring daily energy expenditure (calories/day), daily energy intake (calories/day), daily physical activity, weight gain, and other health measures in a large sample of pregnant mothers. Mothers are recruited to represent a wide range of daily physical activity, from those who are sedentary and plan to remain sedentary through pregnancy to athletes who intend to maintain high exercise workloads. Mothers’ daily activity and weight gain are tracked weekly. Energy expenditure and intake are measured twice for each participant: early and late in pregnancy. Health outcomes are taken from routine medical visits. Maternal Metabolic Limits hypotheses are supported if highly active mothers expend the same amount of calories late in pregnancy as mothers who are more sedentary, and if high levels of exercise negatively impact weight gain. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.