OS021. Risk factors and outcomes of maternal obesity and excessive weight gain during pregnancy.

INTRODUCTION: The prevalence of overweight and obesity among women of reproductive age is increasing. Maternal obesity seems to be associated with short-term and long-term adverse outcomes. Excessive gestational weight gain might also influence the risk of adverse pregnancy outcomes. Not much is known about risk factors of maternal obesity and excessive gestational weight gain. Also, little is known about critical periods of gestational weight gain in relation to adverse pregnancy outcomes. OBJECTIVES: We aimed to determine risk factors and maternal, fetal and childhood consequences of maternal obesity and excessive gestational weight gain. Furthermore, we examined the associations of trimester-specific weight gain with the risk of adverse pregnancy outcomes. METHODS: The study was embedded in a population-based prospective cohort study among 6959 mothers and their children. Maternal anthropometrics were measured in each trimester of pregnancy. Information about maternal weight just before pregnancy, maximum weight during pregnancy and potential socio-demographic and lifestyle related determinants was obtained from questionnaire. Information about gestational hypertensive disorders and birth outcomes was obtained from medical records. Multivariate linear and logistic regression analyses were used. RESULTS: Maternal lower educational level, lower household income, multiparity, and FTO risk allel were associated with an increased risk of maternal obesity, whereas maternal European ethnicity, nulliparity, higher total energy intake, and smoking during pregnancy were associated with an increased risk of excessive gestational weight gain (all p-values <0.05). As compared to normal weight, maternal obesity was associated with increased risks of gestational hypertension (OR 6.31 (95% CI 4.30,9.26)), preeclampsia (OR (3.61 (95% CI 2.04,6.39)), gestational diabetes (OR 6.28 (95%CI 3.01,13.06)), caesarean delivery (OR 1.91 (95% CI 1.46,2.50)), delivering large size for gestational age infants (OR 2.97 (95% CI 2.16,4.08)), and childhood obesity (OR 5.02 (95% CI:2.97,8.45)). Weaker associations of excessive gestational weight gain with these outcomes were observed, with the strongest effects for first trimester weight gain. Weight gain in first and third trimester was associated with the risk of gestational hypertension (OR 1.24 (95% CI 1.12,1.39) and OR 1.27 (95% CI 1.06,1.51) per standard deviation of change in gestational weight gain per week, respectively), whereas weight gain in third trimester was associated with the risk of preeclampsia (OR 1.35 (95% CI 1.08,1.69), per standard deviation of change in gestational weight gain per week). CONCLUSION: Our study shows that maternal obesity and excessive weight gain during pregnancy are associated with socio-demographic, lifestyle, and genetic factors and with increased risks of adverse maternal, fetal and childhood health outcomes. As compared to prepregnancy overweight and obesity, excessive gestational weight gain has a limited influence on adverse pregnancy outcomes.