Association Between Gestational Weight Gain and Maternal Outcomes in Advanced Maternal Age: A Cohort Study on Complex Risk Patterns

Background The association between gestational weight gain (GWG) and maternal outcomes remains controversial in women of advanced maternal age (AMA). This study aims to determine whether the association pattern in AMA women differs from that in the general population. Methods A single-center retrospective cohort study design was employed, including 2,164 women with singleton pregnancies of advanced maternal age who delivered between January 2023 and December 2025. Based on pre-pregnancy Body Mass Index (BMI) and the Chinese "Recommended Standards for Weight Gain during Pregnancy (2022)", total GWG was categorized into three groups: Inadequate, Adequate, and Excessive. Multivariable logistic regression models were used to analyze the associations between GWG categories and gestational diabetes mellitus (GDM), hypertensive disorders of pregnancy (HDP), and postpartum hemorrhage (PPH). Results Multivariable logistic regression analysis showed that, compared to the Adequate GWG group, Excessive GWG was associated with a lower risk of GDM (aOR = 0.699, 95% CI: 0.569–0.859) but a higher risk of HDP (aOR = 1.681, 95% CI: 1.170–2.430). Conversely, Inadequate GWG was associated with a higher risk of GDM (aOR = 1.861, 95% CI: 1.370–2.528). The association between GWG and PPH was not statistically significant. Conclusion This study identifies a complex association between GWG and maternal complications in women of advanced maternal age, particularly an inverse association between excessive weight gain and GDM risk. These findings challenge the uniform applicability of weight gain recommendations derived from the general population to older mothers. However, the inverse relationship with GDM should be interpreted with caution, potentially reflecting the impact of clinical interventions on weight trajectories. The study highlights the need for risk-stratified, individualized management strategies.