Maternal fitness at the onset of the second trimester of pregnancy: correlates and relationship with infant birth weight

BackgroundIt is still unclear whether maternal physical activity and fitness during pregnancy contributes to perinatal health. ObjectivesThe aims of this study were to characterize maternal physical fitness at 16 weeks of pregnancy and to examine its effects on infant birth weight. MethodsMaternal anthropometry (body mass index [BMI] and skin-folds), physical activity, cardiorespiratory fitness (VO(2)peak) and muscular fitness (handgrip strength) were assessed at 16 weeks of gestation in 65 healthy pregnant women. Offspring birth weight was collected from maternal charts after delivery. ResultsA higher VO(2)peak was associated with physical activity spent at sports and exercise before and in early pregnancy (P=0.0005). Maternal BMI was negatively associated with cardiorespiratory fitness (P<0.0001) but positively related to muscular strength (P=0.0001). Unlike maternal cardiorespiratory fitness, handgrip strength was positively associated with infant birth weight (r=0.34, P=0.0068) even after adjustment for confounders (adjusted r=0.27, P=0.0480). ConclusionA positive relationship between maternal muscular fitness and infant birth weight highlighted maternal strength in pregnancy as a new determinant of infant birth weight.