PS-356 Association Between Maternal Pre-pregnancy Body Mass Index And Size At Birth In RibeirÃo Preto, SÃo Paulo, Brazil

Abstract

Background and aims Fetal growth is determined partially by maternal characteristics such as pre-pregnancy weight. Maternal pre-pregnancy anthropometry is useful to estimate birth weight and the risk of various adverse perinatal outcomes. We studied the relationship between pre-pregnancy anthropometry and newborn size. We estimated the risk of low birth weight (LBW, <2,500 g) or high birth weight (HBW, ≥4,000 g), preterm (PT), small (SGA) or large (LGA) for gestational age in a birth cohort from Ribeirão Preto, Brazil, in 2010, according to maternal pre-pregnancy body mass index (BMI). Methods A convenience cohort of 1370 pregnant women living in the city was evaluated between 22-25 weeks of gestation, and their respective newborns. Standardised questionnaires were applied during pregnancy and soon after birth. The dependent variables were LBW/HBW, PT and SGA/LGA. The independent variable was maternal pre-pregnancy BMI, classified as overweight (BMI between 25 and 29.9 kg/m2) and obese (BMI≥30 kg/m2). Logistic regression models were adjusted for biological, sociodemographic and pregnancy-related variables. Results A high prevalence of overweight-obesity (39.6%) was observed and gestational weight gain was above international recommendations, especially among obese mothers. Overweight and obesity before pregnancy, according to pre-pregnancy BMI showed high risk of HBW (RR 2.1, 95% CI 1.09-3.68 and RR 2.58, 95% CI 1.36-4.91, respectively) and LGA infants (RR 1.96, 95% CI 1:10-3:49 and 3:47 RR, 95% CI 1.95-6.16, respectively), but not with LBW, SGA or PT. Conclusions In this population, frequencies of overweight and obesity were elevated and were independently associated with HBW and LGA.