Resistance exercise training during pregnancy and newborn's birth size: a randomised controlled trial

Objective: We examined the effect of light intensity resistance exercise training performed during the second and third trimester of pregnancy on the newborn's birth size. We also studied the association between maternal body weight prior to pregnancy and newborn's birth size. Design: Randomised controlled trial. Subjects: We randomly assigned 160 sedentary gravidae to either a training (n = 80) or a control (n = 80) group. The training programme focused on light resistance and toning exercises (three times per week, 35-40 min per session). We recorded the Apgar score, birth weight, birth length, and head circumference of the newborn, as well as gestational age at time of delivery from hospital perinatal records. We also measured maternal weight and height before parity and gestational weight gain. Results: Maternal characteristics neither differed between groups (all P > 0.1) nor newborn characteristics (all P > 0.1). Maternal body weight was positively and significantly associated with newborn's birth weight and length only in the control group (beta = 19.20 and 0.065, respectively, P < 0.01). Conclusion: Light intensity resistance training performed over the second and third trimester of pregnancy does not have a negative impact on the newborn's body size or overall health. Exercise interventions might attenuate the adverse consequences of maternal body weight before pregnancy on the newborn's birth size. International Journal of Obesity (2009) 33, 1048-1057; doi: 10.1038/ijo.2009.150; published online 28 July 2009