Objective: To examine the association between maternal pre-pregnancy weight status and the risk of stillbirth, pre-eclampsia and preterm delivery.
Design: Hospital-based cohort study using prospectively recorded data.
Setting: Ten public hospitals in Buenos Aires, Argentina.
Population: 46,964 pregnant women who had a delivery during 2003-2006.
Methods: Prepregnancy body mass index (BMI) was used to categorize women in four weight categories from underweight to obese. The reference group were women with BMI between 18.5 and 24.9. Crude and adjusted odds ratios were calculated using multiple logistic regression analysis.
Main outcome: Preterm birth, pre-eclampsia and stillbirth.
Results: The risk of preterm delivery decreased with increasing BMI, with the highest risk among underweight women (OR: 1.45; 95% CI: 1.26-1.67), and the lowest risk among the overweight. The risk of pre-eclampsia was highest among overweight (OR: 1.55; 95%CI: 1.30-1.86) and obese women (OR: 3.10; 95%CI: 2.54-3.78). Obese or overweight women did not have an increased risk of stillbirth in this study.
Conclusions: Overweight and obese women have an increased risk for pre-eclampsia, while underweight women have an increased risk for preterm delivery. There is a high prevalence of overweight women in the obstetric population in Buenos Aires.