Association of pre-pregnancy body mass index and gestational weight gain with neonatal outcomes in elderly gravida for second child / 中华围产医学杂志

ABSTRACT

Objective:To investigate the maternal pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) during pregnancy at advanced maternal age for their second child at advanced maternal age, and to explore the relationship with neonatal outcomes.Methods:This study involved 1 965 women of advanced maternal age who delivered the second child in the Northwest Women's and Children's Hospital from July 1 to December 31, 2017. Clinical data of these women and their newborns were collected through the electronic medical record information system. According to pre-pregnancy BMI, all subjects were divided into four groups: underweight group (<18.5 kg/m 2, n=139), normal weight group (18.5-23.9 kg/m 2, n=1 342), overweight group (24.0-27.9 kg/m 2, n=404) and obese group (≥28.0 kg/m 2, n=80). According to the GWG standard recommended by the American Institute of Medicine (IOM) in 2009, they were also divided into three groups: inadequate GWG group ( n=478), normal GWG group ( n=884) and excessive GWG group ( n=603). Mann-Whitey U test, Chi-square test or Fisher's exact test were used as statistical methods. Effects of pre-pregnancy BMI and GWG on gestational age and birth weight of the newborns were analyzed by binary and multi-class logistic regression models. Results:The median pre-pregnancy BMI of the 1 965 women was 22.1 (20.3-23.9) kg/m 2 and patients with abnormal pre-pregnancy BMI accounted for 31.7% (623/1 965). Their median GWG was 13.0 (10.0-16.0) kg and 55.0% (1 081/1 965) of them were abnormal. Compared with normal pre-pregnant weight women, overweight and obesity subjects were associated with increased risks of preterm birth ( OR=2.100, 95% CI: 1.398-3.156), low birth weight infants (LBWI) ( OR=3.187, 95% CI: 1.892-5.367) and macrosomia ( OR=1.758, 95% CI: 1.182-2.614); pre-pregnancy underweight reduced the incidence of large for gestational age (LGA) infants ( OR=0.476, 95% CI: 0.236-0.960). Compared with the normal GWG group, the inadequate GWG group had increased risks of preterm birth ( OR=2.316, 95% CI: 1.530-3.505) and LBWI ( OR=1.850, 95% CI: 1.103-3.104), while the excessive GWG group showed increased risks of macrosomia ( OR=1.828, 95% CI: 1.225-2.726) and LGA infants ( OR=1.955, 95% CI: 1.448-2.640), but a reduced risk of LBWI ( OR=0.359, 95% CI: 0.193-0.667) and small for gestational age infants ( OR=0.452, 95% CI: 0.240-0.852). Conclusions:Both abnormal pre-pregnancy BMI (underweight, overweight and obese) and GWG (inadequate and excessive) have adverse effects on neonatal outcomes in women of advanced age in pregnancy for their second baby. Weight management should be addressed during the whole pregnancy, including both adjusting the pre-pregnancy BMI to normal range and maintaining reasonable GWG, so as to reduce potential adverse outcomes in newborns.