Gestational Weight Gain in the First Two Pregnancies and Perinatal Outcomes in the Second Pregnancy

Background Gestational Weight Gain (GWG) below or above the Institute of Medicine (IOM) recommendations increases the risk of adverse pregnancy outcomes. However, it remains unknown whether the risk of adverse outcomes is affected by GWG in a previous pregnancy. We examined associations between GWG in the index (second) pregnancy and pregnancy outcomes, including preterm delivery and small for gestational age (SGA), while taking into consideration GWG in the first pregnancy. Methods In a population-based cohort study (n = 210 564), using the Missouri maternally-linked birth registry (1989-2005), we used multivariable Poisson regression with robust error variance stratified by prepregnancy body mass index (BMI) to evaluate associations between GWG in the index pregnancy and a composite indicator of GWG in the first and second pregnancies and our outcomes of interest, after controlling for sociodemographic and pregnancy-related confounders. Results Associations between GWG in the index pregnancy and pregnancy outcomes were moderated by GWG in the first pregnancy. Despite having GWG within recommendations in the index pregnancy, women had increased risk of preterm delivery and SGA if they had suboptimal GWG in their first pregnancy. Also, women having suboptimal GWG in the index pregnancy had increased risk of preterm delivery only if their GWG in the first pregnancy was also suboptimal. Conclusions The observation that women who have GWG within recommendations in a current pregnancy may still have increased risk of adverse outcomes if they had suboptimal GWG in the first pregnancy has considerable clinical and public health implications.