Prenatal Exposure to Gestational Diabetes Mellitus Is Associated With Greater Pre‐Pubertal BMI Growth and Faster Post‐Pubertal Cortical Thinning During Peri‐Adolescence

Background The longitudinal trajectory of body mass index (BMI) and brain structure development during peri‐adolescence is not clearly defined in offspring prenatally exposed to gestational diabetes mellitus (GDM) versus unexposed offspring. Methods Participants between age 9 and 10 years ( N = 9583) were included from the Adolescent Brain and Cognitive Development (ABCD) Study and followed yearly through 4‐year follow‐up. GDM and puberty status were self‐reported. BMI was calculated yearly, and MRI assessed brain structure biennially. Mixed‐effects models analysed trajectories of BMI and brain structural measures between groups controlling for sociodemographic covariates, and linear spline was defined with a knot at the onset of puberty. Results There was an interaction of exposure by age in change in BMI [β (95% CI) = 0.032 (0.008, 0.056), p = 0.009] and mean cortical thickness [β (95% CI) = −0.038 (−0.071, −0.004), p = 0.027]. The former was driven by greater pre‐pubertal increases in BMI [β (95% CI) = 0.051 (0.002, 0.100), p = 0.043], whereas the latter was driven by faster post‐pubertal declines in cortical thickness among GDM‐exposed offspring [β (95% CI) = −0.051 (−0.095, −0.007), p = 0.046]. Conclusion Prenatal GDM exposure is associated with greater pre‐pubertal increases in BMI and faster post‐pubertal cortical thinning in youth aged between 9 and 15.