Prepregnancy body mass index and gestational weight gain with the outcome of pregnancy: a 13-year study of 292,568 cases in China

We aimed to investigate the combined associations of prepregnancy body mass index (BMI) and gestational weight gain (GWG) with pregnancy outcomes in Chinese women. Data for 292,568 singleton term pregnancies were selected from 1993 to 2005 based on the Perinatal Health Care Surveillance System, with anthropometric measurements being collected prospectively. Prepregnancy BMI was categorized according to the definitions of the World Health Organization (WHO). Total GWG was categorized into four groups. Adjusted associations of prepregnancy BMI and GWG with outcomes of interest were estimated using logistic regression analyses. GWG was categorized as below, within and above the Institute of Medicine (IOM) (2009) recommendations. Maternal overweight and high GWG or GWG above the IOM recommendation were associated with hypertensive disorders complicating pregnancy, cesarean delivery, macrosomia and large-for-gestational-age (LGA) infants. Maternal underweight and low GWG or GWG below the IOM recommendation were risk factors for low-birth-weight (LBW) and small-for-gestational-age (SGA) infants. Moreover, being overweight [odds ratio (OR) 1.2, 95 % confidence interval (CI) 1.0-1.3) and having a low weight gain (OR 1.1, 95 % CI 1.0-1.1) increased the risk of newborn asphyxia. Being overweight/obese and having a high weight gain, as well as being underweight and having a low weight gain, were associated with increased risks for adverse pregnancy outcomes in Chinese women.