856A gestational age specific prognostic model for adverse perinatal events in obese women

Abstract

Abstract Background Obesity is one of the most preventable pre-pregnancy risk factors for adverse perinatal events. Despite this, there are few body-mass-index (BMI) specific prognostic models for timing of delivery associated with the lowest number of adverse perinatal events. Our aim was to build a predictive model to quantify gestational age-specific rates of adverse birth outcomes in obese women with and without additional risk factors. Methods All singleton births at ≥ 34 weeks’ gestation in British Columbia, Canada, 2008-2017 (n = 283,697) were included and data were obtained from the British Columbia Perinatal Database Registry. A multivariable Cox proportional hazards model including demographic and obstetric risk factors was used to estimate gestational age specific risk of composite perinatal mortality and severe morbidity. Results Among all women, 13.1% were obese (pre-pregnancy BMI ≥30m/kg2), 60.1% had normal BMI (18.5-24.9 m/kg2). In high-risk obese women (nulliparous with chronic hypertension, and diabetes), adjusted outcome rates (per 1000 ongoing pregnancies) were 7.5 at 34-36 weeks, 20.4 at 37-39 weeks, and 83.5 at ≥ 40 weeks’ gestation. In all obese women, the rates were 1.93, 6.27, and 18.5 per 1000 ongoing pregnancies, respectively. In contrast, on average these rates were 1.14, 4.03 and 11.6 per 1000 ongoing pregnancies, respectively, among women with normal BMI. Conclusions Obese women are at increased risk of poor perinatal outcomes at all gestational ages. These risks are compounded by other conditions known to effect perinatal outcomes. Key messages Obese women require specific guidelines for timing of optimal delivery.