Maternal pre‐pregnancy body mass index, gestational weight gain trajectory, and risk of adverse perinatal outcomes

To evaluate the relationships of pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) trajectory with adverse perinatal outcomes (APOs).A retrospective cohort study was conducted in China, and 12 855 women who had a singleton birth were included. The WHO classification categorized pre-pregnancy BMI, and five GWG trajectories were identified using the latent class growth model.The adjusted odds ratios for the risks of cesarean delivery, preterm birth, and large-for-gestational-age (LGA) infant were significantly higher in women with whoe were overweight or obese pre-pregnancy, but were lower in underweight (except preterm birth) than in normal weight women. Five GWG trajectories were identified: (1) retaining GWG (6.6 kg), (2) moderately slow GWG (10.5 kg), (3) moderate GWG (13.7 kg), (4) moderately fast GWG (16.3 kg), and (5) rapid GWG (19.8 kg). Compared with women in trajectory 3, the risks of cesarean delivery and LGA increase by about 35%-96% for the women in trajectory 4 or 5, whereas the women in trajectory 1 or 2 are inclined to have a higher risk of small for gestational age, but lower risk of LGA. Association of GWG trajectory with APOs varies across pre-pregnancy BMI subgroups.This study highlights the influence of inappropriate pre-pregnancy maternal weight and GWG trajectories on the risk of APOs.