Impact of a walking intervention during pregnancy on post-partum weight retention and infant anthropometric outcomes.

Few studies have investigated the impact of lifestyle interventions during pregnancy on post-partum weight retention and infant growth. Thirty seven previously non-exercising, overweight or obese pregnant women were randomly assigned to a walking intervention or non-intervention control. For the follow-up study, weight of the mother and weight, length and body composition of the infant were collected at 1 month post-partum (n=37) and 6 months post-partum (n=33). Analysis of variance and linear regression were conducted to determine the differences and association in maternal post-partum weight retention and child outcomes. At 6 months post-partum, weight retention of obese women in the intervention group (Int-OB) was -0.10±8.11 kg; while, obese women in the control group (Con-OB) was 6.35±7.47 kg. A significantly higher percentage of Con-OB women retained more than 5 kg at 6 months post-partum (P=0.046). Even though statistically non-significant between the groups, the growth trend observed among offspring of obese women in the control group was consistently higher than the offspring of obese women in the intervention group from birth to 6-months. Third trimester gestational weight gain rate significantly predicted 6-m weight-for-length z-score after controlling for birth weight, treatment group and pre-pregnancy body mass index (r 2=0.31, β=1.75, P=0.03). The reduced post-partum weight retention observed among the obese women in the intervention group may be explained in part by the lifestyle modification during pregnancy.