Mediating role of body mass index and fetal fraction in the association between advanced maternal age and gestational diabetes mellitus risk: a retrospective non-invasive prenatal testing cohort study

AMA significantly increases GDM risk, partly mediated by elevated BMI and reduced NIPT-derived FF. These findings highlight the role of maternal metabolic and placental factors as key intermediaries in AMA-related GDM, offering insights for targeted prenatal risk stratification and intervention. Given the retrospective design, causal inference cannot be established.