Dietary quality is associated with lower postpartum weight retention among women with prior gestational diabetes in a sub-high altitude region of China

Background Women with a history of gestational diabetes mellitus (GDM) are at high risk of long-term metabolic disorders, and postpartum weight retention (PPWR) may further accelerate this progression. However, evidence regarding the independent roles of dietary quality and physical activity in sub-high altitude regions remains limited. This study aimed to evaluate the associations between lifestyle behaviors and PPWR among women with prior GDM living in southwestern China. Methods This cross-sectional study included 141 women with a history of GDM who were 1–3 years postpartum and residing in Dali, a sub-high altitude region of China. Dietary quality was assessed using a localized semi-quantitative food frequency questionnaire, and physical activity was evaluated using the International Physical Activity Questionnaire–Short Form. Multivariable linear regression models were used to identify independent correlates of continuous PPWR after adjustment for demographic, obstetric, and lifestyle covariates. Sensitivity analysis was performed using binary logistic regression with clinically significant PPWR (≥5 kg) as the outcome. Results Higher dietary quality was independently associated with lower PPWR in the fully adjusted model ( B = −0.099, 95% CI: −0.175 to −0.023, p = 0.011). Each one-point increase in dietary quality score was associated with an approximately 0.1 kg lower PPWR; equivalently, a 10-point increase in dietary quality score was associated with an approximately 1.0 kg reduction in PPWR. This association remained stable in sensitivity analysis (OR = 0.937, 95% CI: 0.885–0.991, p = 0.022). Although physical activity showed an inverse association with PPWR in univariate analysis, it was no longer statistically significant after multivariable adjustment. Lower pre-pregnancy body mass index and higher neonatal birth weight were also independently associated with greater PPWR. Conclusion Among women with prior GDM living in a sub-high altitude region, better dietary quality was independently associated with lower long-term PPWR, whereas self-reported physical activity was not. These findings support region-specific dietary counseling as a potentially important strategy for postpartum metabolic risk reduction in high-risk women.