Association of Second and Third Trimester Weight Gain in Pregnancy with Maternal and Fetal Outcomes

Objective: To investigate the association between weekly weight gain, during the second and third trimesters, classified according to the 2009 Institute of Medicine (IOM/NRC) recommendations, and maternal and fetal outcomes. Methods: Gestational weight gain was evaluated in 2,244 pregnant women of the Brazilian Study of Gestational Diabetes (Estudo Brasileiro do Diabetes Gestacional - EBDG). Outcomes were cesarean delivery, preterm birth and small or large for gestational age birth (SGA, LGA). Associations between inadequate weight gain and outcomes were estimated using robust Poisson regression adjusting for pre-pregnancy body mass index, trimester-specific weight gain, age, height, skin color, parity, education, smoking, alcohol consumption, gestational diabetes and hypertensive disorders in pregnancy. Results: In fully adjusted models, in the second trimester, insufficient weight gain was associated with SGA (relative risk [RR] 1.72, 95% confidence interval [CI] 1.26-2.33), and excessive weight gain with LGA (RR 1.64, 95% CI 1.16-2.31); in third trimester, excessive weight gain with preterm birth (RR 1.70, 95% CI 1.08-2.70) and cesarean delivery (RR 1.21, 95% CI 1.03-1.44). Women with less than recommended gestational weight gain in the 2nd trimester had a lesser risk of cesarean deliveries (RR 0.82, 95% CI 0.71-0.96) than women with adequate gestational weight gain in this trimester. Conclusion: Though insufficient weight gain in the 3rd trimester was not associated with adverse outcomes, other deviations from recommended weight gain during second and third trimester were associated with adverse pregnancy outcomes. These findings support, in part, the 2009 IOM/NRC recommendations for nutritional monitoring during pregnancy.