Exercise FITT-V During Pregnancy: Dose-Dependent Reduction in Infant Cellular Lipid Content and Whole-Body Fat

Introduction: Modifiable health behaviors such as exercise regulate adiposity in adults, but the effects of exercise during pregnancy on infant adiposity remain understudied. This report analyzed the relationship between prenatal exercise frequency, intensity, time, type and volume (FITT-V) and infant adiposity, to better guide prenatal exercise prescription. Methods: Female participants (body mass index = 29.0 kg/m2, 30.5 years of age, with gravida = 1 and parity = 0, VO2peak = 21.9 ml/kg/min, and pregnant for 39.6 weeks) were randomized to supervised exercise (aerobic, resistance, combination) or attention-control for ~24 weeks during pregnancy. FITT-V metrics were analyzed from session records. Infant mesenchymal stem cells (MSCs), a model of infant adiposity, were collected from umbilical cord at delivery, adipogenically differentiated, and stained for lipids. Infant body fat percentage was estimated from skinfolds measured at one month of age. Results: Higher weekly exercise volume correlated with lower infant body fat (R2 = .12, p = .03) and MSC lipids (R2 = .13, p = .01). Weekly exercise frequency (R2 = .06, p = .10) and total volume (R2 = .19, p = .002) influenced adiposity. Supscapular skinfolds were notably affected by exercise (R2 = .27, p < .001). Conclusions: In utero exposure to exercise beyond minimum recommendations is associated with reduced infant adiposity. Specifically, our findings suggest exercising below 450 MET*minutes per week, e.g., exercising at an average of 3 METs for 150 minutes per week, or 5 METs for 90 minutes per week, excludes individuals from these offspring health benefits.