Association between gestational weight gain and adverse pregnancy outcomes in advanced maternal age: a retrospective cohort study

Objective To investigate the association between gestational-age-adjusted gestational weight gain (GWG) and adverse maternal and neonatal outcomes among women of advanced maternal age (AMA). Methods This retrospective cohort study included 714 singleton pregnant women aged 35 years or older who received antenatal care and delivered at Hebei Provincial Hospital of Traditional Chinese Medicine between January 2022 and December 2025. GWG was calculated as the difference between pre-delivery weight and pre-pregnancy weight. Based on the Chinese standard WS/T 801–2022, participants were classified into insufficient, adequate, and excessive GWG groups using gestational-age-adjusted recommended ranges according to pre-pregnancy body mass index. Baseline characteristics, pregnancy complications, maternal outcomes, and neonatal outcomes were compared across GWG categories. Multivariable logistic regression models were used to estimate the associations between GWG categories and adverse outcomes, with adequate GWG as the reference group. Results Among the 714 women included in the analysis, 112 (15.7%) had insufficient GWG, 282 (39.5%) had adequate GWG, and 320 (44.8%) had excessive GWG. After adjustment for potential confounders, insufficient GWG was associated with increased risks of premature rupture of membranes (aOR = 1.65, 95% CI: 1.01–2.69), gestational hypothyroidism (aOR = 1.89, 95% CI: 1.08–3.30), and low birth weight (aOR = 2.12, 95% CI: 1.05–4.29). Excessive GWG was associated with increased risks of cesarean delivery (aOR = 1.47, 95% CI: 1.04–2.08), postpartum anemia (aOR = 1.78, 95% CI: 1.12–2.84), preeclampsia (aOR = 1.71, 95% CI: 1.01–2.89), and macrosomia (aOR = 2.12, 95% CI: 1.16–3.88). The association between GWG category and preterm birth was attenuated after adjustment. Sensitivity analysis restricted to term pregnancies yielded generally consistent results. Conclusion Among women of advanced maternal age, both insufficient and excessive gestational-age-adjusted GWG were associated with increased risks of adverse maternal and neonatal outcomes. These findings suggest that individualized monitoring and management of GWG during pregnancy may help improve pregnancy outcomes in this high-risk population.