The Effect of Maternal Physical Activity and Gestational Weight Gain on Placental Efficiency.

INTRODUCTION Adherence to physical activity (PA) and gestational weight gain (GWG) recommendations during pregnancy has been shown to improve maternal and fetal health outcomes, including reducing the risk for chronic diseases. Limited research has evaluated the effect of meeting PA in combination with GWG recommendations on placental efficiency (Pl-E), a surrogate marker of the placenta's ability to exchange nutrients and gas based on surface area. The purpose of this study was to measure and compare Pl-E based on meeting PA and GWG recommendations. METHOD Healthy pregnant women (n=61) wore accelerometers in their second and third trimester to objectively measure PA. Women were classified as active or inactive at each timepoint based on meeting the 2019 Canadian prenatal PA guidelines. Total GWG was calculated as weight measured in the third trimester minus self-reported pre-pregnancy weight, and categorized as insufficient (n=19), adequate (n=22), and excessive (n=20) according to the 2009 Institute of Medicine guidelines. Placental weight (PW) and birthweight (BW) were measured within 30 min of delivery and 24-48 hours post-delivery, respectively. Pl-E was determined in three ways: BW:PW ratio, residual BW, and measured BW, with a higher value indicating better Pl-E. Pl-E was compared by PA and GWG status using a two-way ANOVA. RESULTS No differences were found in the BW:PW ratio, or residual BW corresponding to PA and GWG status. Measured BW was significantly higher in newborns of women who gained weight excessively compared to those who gained insufficient weight (p<0.05). CONCLUSION These findings suggest that prenatal PA does not compromise Pl-E; however, further research is required to evaluate the potential mechanistic benefits of meeting PA and GWG guidelines on the placenta.