Timing of Gestational Weight Gain and Adverse Perinatal Outcomes in Overweight and Obese Women.

Objective: To evaluate whether inadequate or excessive gestational weight gain before the third trimester is associated with adverse pregnancy outcomes, and to evaluate the association of weight gain in the third trimester with fetal growth.

Methods: This was a retrospective cohort study of all eligible overweight and obese women with singleton pregnancies delivered at an academic institution between 2012 and 2014. Our primary exposure was inadequate or excess gestational weight gain during the first and second trimesters. Outcomes included small- (SGA) or large- (LGA) for-gestational-age birth weight as well adverse maternal outcomes and composite neonatal morbidity. Multivariable logistic regression was used to assess the relationship between weight gain and perinatal outcomes, and stratified analyses evaluated the relationship between third trimester weight gain and birth weight category.

Results: Of the 5,814 women, 1,280 (22%) had adequate, 1,428 (24.6%) had inadequate, and 3,106 (53.4%) had excessive weight gain in the first and second trimesters. Women with inadequate early gestational weight gain were more likely to deliver an SGA neonate (adjusted odds ratio [aOR] 1.59, 95% CI 1.23-2.06) and less likely to deliver an LGA neonate (aOR 0.73, 95% CI 0.54-0.98), whereas those with excessive early gestational weight gain were less likely to deliver an SGA neonate (aOR 0.66, 95% CI 0.52-0.85) and more likely to deliver an LGA neonate (aOR 1.66, 95% CI 1.32-2.1). Higher weight gain in the third trimester was associated with increased risk for LGA birth weight, but third trimester weight gain was not related to SGA birth weight.

Conclusion: Early gestational weight gain is associated with birth weight category. Modifying weight gain in the third trimester may limit the risk for LGA birth weight, but higher weight gain in late gestation does not alter the association between inadequate early weight gain and the risk for SGA.