Maternal recreational physical activity is associated with plasma leptin concentrations in early pregnancy

Background: A limited amount of literature suggests that plasma leptin concentrations are reduced with habitual physical activity in men and non-pregnant women. We investigated the relationship between maternal physical activity and plasma leptin during early pregnancy. Methods: The study population included 879 normotensive, non-diabetic pregnant women who reported physical activity type, frequency, and duration in early pregnancy. Plasma leptin, measured in blood samples collected <16 weeks gestation, were determined using enzyme immunoassays. Weekly duration (h/week) and energy expended on recreational physical activity [metabolic equivalent score (MET)-h/week] were categorized by tertiles among active women. Physical activity intensity was categorized as none, moderate (<6 MET) and vigorous (≥6 MET). Differences in leptin concentrations across categories were estimated using linear regression procedures. Results: Mean leptin was 5.8 ng/ml lower among active versus inactive women (P = 0.001). Mean leptin was lower among women in the highest levels (> 12.8 h/week) of time performing physical activity (-8.1 ng/ml, P < 0.001) and energy expenditure (>70.4 MET-h/week) (-8.3 ng/ml, P = 0.001) compared with inactive women. Leptin was inversely associated with the intensity of physical activity. Conclusions: Our findings are consistent with other reports suggesting an independent inverse relationship between habitual physical activity and leptin concentrations. Our lindings extend the literature to include pregnant women.