Maternal Gestational Diabetes and Trajectories of Offspring Fat–Lean Balance in the Millennium Cohort Study

AIMS: We aimed to examine whether offspring exposed to maternal gestational diabetes mellitus (GDM) had different fat-lean balance trajectories from unexposed offspring and whether the estimated associations were attenuated after adjustment for maternal pre-pregnancy adiposity. METHODS: Using UK Millennium Cohort Study data, we analysed body composition outcomes, including fat mass (FM), body fat percentage (BF%), fat mass index (FMI), fat-free mass index (FFMI), and the FMI/FFMI ratio. Linear mixed-effects models characterised body composition trajectories from ages 7-17 years, with additional adjustment to assess the attenuation of the estimates after accounting for maternal pre-pregnancy adiposity. RESULTS: The analysis included 14 329 offspring, of whom 170 were exposed to maternal GDM. In the primary adjusted model, GDM-exposed offspring had higher model-predicted values for all body composition indices than unexposed offspring across the observed ages. GDM-by-age interaction terms indicated age-varying between-group differences for FM, FMI, and the FMI/FFMI ratio (all p < 0.05), with borderline evidence for BF% (p = 0.050) and no clear evidence for FFMI. After additional adjustment for maternal pre-pregnancy adiposity, the estimated between-group differences were attenuated, and some age-specific contrasts, particularly at age 7 years, were no longer statistically significant. Nevertheless, age-varying between-group patterns remained evident for several body composition indices. CONCLUSION: Maternal GDM exposure was associated with age-varying differences in offspring fat mass and fat-lean balance during childhood and adolescence, and these associations were attenuated after adjustment for maternal pre-pregnancy adiposity.