Impact of body mass index before pregnancy and weight gain during pregnancy on pregnancy outcomes

  Objective  To explore the effects of pre-pregnancy body mass index (BMI) and excessive gestational weight gain on pregnancy outcomes of pregnant women.

  Methods  The clinical data of 1 427 pregnant women was retrospectively analyzed. According to the BMI before pregnancy, these pregnant women were divided into thin group (BMI<18.5 kg/m²), normal group (BMI 18.5 kg/m²~<25.0 kg/m²), overweight group and obese group (BMI ≥ 25.0 kg/m²). According to the weight gain criteria recommended by the Institute of Medicine in 2009, the pregnant women were divided into insufficient weight gain group, normal weight gain group, and excessive weight gain group. Pregnancy outcomes of different groups were compared, and the effect of adjusted pregnancy weight gain on adverse pregnancy outcomes was observed.

  Results  The incidence rates of adverse pregnancy outcomes such as hypertensive disorder complicating pregnancy, gestational diabetes, postpartum hemorrhage, fetal macrosomia, low birth weight, premature delivery and cesarean section in the overweight and obese group were higher. Among them, the incidence of adverse pregnancy outcomes such as hypertensive disorder complicating pregnancy, gestational diabetes, postpartum hemorrhage and cesarean section showed statistically significant differences(P<0.05). In the excessive gestational weight gain group, incidence rates of hypertensive disorder complicating pregnancy, postpartum hemorrhage, fetal macrosomia and cesarean section were higher. Among them, adverse pregnancy outcomes including hypertensive disorder complicating pregnancy, postpartum hemorrhage and fetal macrosomia showed significant differences (P<0.05). Area under receiver operating curve (ROC) by pre-pregnancy overweight and obesity predicting premature birth was 0.712, and was 0.684 by excessive gestational weight gain predicting fetal macrosomia, and the prediction effects were both acceptable (P<0.05). The incidence of gestational diabetes mellitus, anemia, postpartum hemorrhage and adverse pregnancy outcomes in macrosomia were significantly decreased in the normal weight gain group when the weight gain value was adjusted to 10.5~15.0 kg.

  Conclusion  Overweight BMI before pregnancy and abnormal body mass gain during pregnancy both increase the risk of adverse pregnancy outcomes, and BMI before pregnancy and weight gain during pregnancy can predict adverse pregnancy outcomes.