The role of social determinants of health in post-diagnosis gestational weight gain trajectories among women with gestational diabetes mellitus: a multicenter cohort using latent class linear mixed models

Excessive gestational weight gain (GWG) is common among women with gestational diabetes mellitus (GDM) and is associated with adverse maternal and neonatal outcomes. However, the influence of social determinants of health (SDOH) on GWG trajectories in this population remains poorly understood. This study aimed to characterize GWG trajectories and evaluate how SDOH influence these patterns. We conducted a multicenter cohort study of women with GDM who delivered at four hospitals in Wuhan, China. GWG trajectories were based on at least three weight measurements from GDM diagnosis to delivery, with gain defined as current weight minus pre-pregnancy or early-pregnancy weight measured before 8 weeks, and were modeled using latent class linear mixed models. SDOH was assessed using 19 indicators across five dimensions, summarized into a composite index, and further divided into three tertiles. Associations between SDOH classes and GWG trajectories were examined with multinomial logistic regression adjusted for maternal age, pre-pregnancy body mass index (BMI), education, employment, and parity. Subgroup analyses were conducted according to pre-pregnancy BMI (< 24.0 vs. ≥ 24.0 kg/m²). Among 1,916 women, three GWG trajectories were identified: low weight gain (33.40%), moderate weight gain (50.42%), and high weight gain (16.28%). SDOH were categorized into three tertile-based classes: Class 1 (most advantaged), Class 2 (intermediate), and Class 3 (most disadvantaged). In the fully adjusted multinomial logistic regression model G, compared with women in Class 1, those in Class 3 had higher odds of belonging to the high weight gain trajectory rather than the moderate trajectory (aOR = 2.18, 95% CI 1.49–3.20). In subgroup analyses, among women with pre-pregnancy BMI < 24.0 kg/m², both Class 2 and Class 3 were associated with higher odds of the high weight gain trajectory (Class 2: aOR = 1.56, 95% CI 1.03–2.37; Class 3: aOR = 3.16, 95% CI 1.99–5.01), whereas no significant association with the high weight gain trajectory was observed among women with pre-pregnancy BMI ≥ 24.0 kg/m². Among women with GDM, GWG follows three distinct trajectories. Greater social disadvantage is associated with a higher likelihood of high GWG. These findings support the early identification of socially disadvantaged women and the development of BMI-specific, socially informed prenatal weight management strategies. ChiCTR2200063189, registered 01 September 2022.