Objective To analyze the impact of pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) on delivery mode and maternal-infant outcomes in women of advanced maternal age.

Methods Clinical data of 800 women of advanced maternal age were collected. The participants were divided into low-body-weight group, normal-body-weight group, overweight group and obese group according to pre-pregnancy BMI, and also divided into insufficient-gain group, normal-gain group and excessive-gain group according to GWG. General data, delivery mode and adverse maternal-infant outcomes were compared among groups. Binary logistic regression was used to analyze the effects of pre-pregnancy BMI and GWG on adverse maternal-infant outcomes after adjusting for confounding factors.

Results There were statistically significant differences in education level, place of residence and history of previous cesarean section among groups with different pre-pregnancy BMI (P＜0.01), while no significant differences were found in age, height, gravidity, parity and pregnancy interval (P＞0.05). Statistically significant differences were observed in education level, place of residence, gravidity, parity and history of previous cesarean section among groups with different GWG (P＜0.01), whereas age, height and pregnancy interval showed no inter-group differences (P＞0.05). Statistically significant differences were found in the incidence of gestational hypertension, gestational diabetes mellitus, premature rupture of membranes, placenta previa, postpartum hemorrhage, preterm birth and macrosomia among different pre-pregnancy BMI groups and different GWG groups (P＜0.05 to P＜0.01). Compared with the normal-body-weight group, the incidence of above-mentioned complications increased significantly in the obesity group (P＜0.01). Compared with the GWG-normal group, the incidence of above-mentioned complications increased significantly in the GWG-excessive group (P＜0.01). After adjustment for confounding factors, compared with the normal-body-weight group and GWG-normal group, overweight group and GWG-excessive group presented higher risks of gestational hypertension, premature rupture of membranes, placenta previa and macrosomia (P＜0.05 to P＜0.01); obese group had increased risks of gestational hypertension, gestational diabetes mellitus, premature rupture of membranes, placenta previa, postpartum hemorrhage and macrosomia (P＜0.05 to P＜0.01); both low-body-weight group and obese group showed a higher risk of preterm birth (P＜0.05 to P＜0.01); GWG-insufficient group had a higher risk of placenta previa (P＜0.05).

Conclusions Pre-pregnancy overweight, obesity and excessive GWG can increase the risks of cesarean section and adverse maternal-infant outcomes in advanced maternal age women.