March 2025
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Importance: Maternal diabetes (MD) and maternal obesity (MO) have been robustly established to confer health risks in offspring. Additionally, mounting evidence suggests that these fetal programming effects vary by sex, but whether these factors independently or interactively influence infant brain development remains unclear. Objectives: To characterize interactions between MD, MO, and sex on offspring subcortical brain volumes. Design, setting and participants: This was a cross-sectional study of 1,966 infants from six international cohorts. Exposures: MD and MO Main outcomes and measures: MRI-based subcortical brain volumes (thalamus, amygdala, hippocampus, pallidum, putamen, caudate) were segmented and mixed effects models were used to examine associations, controlling for age at scan, prematurity, birthweight, maternal education, and intracranial volume. Backward elimination regression was used to identify the best fitting model (3-way interaction, 2-way interaction, no interaction) for each region and false discovery rate (FDR) corrections were applied. Results: Of 1,966 infants, 46% were female (N=909), 9% were exposed to MD (N=172), and 21% were exposed to MO (N=386). MRI scans were performed at (mean±SD) 25.9±18.8 days of age. There was a significant interaction between MD, MO and sex in the thalamus (standardized β=−0.32, 95%CI −0.54 to −0.11, FDR corrected P=0.014). In female infants, MD (standardized β=-0.10, 95%CI −0.02 to −0.003, P=0.04) and MO (standardized β =−0.09, 95%CI −0.14 to −0.03, P=0.003) were independently and negatively associated with thalamic volume. In males, a significant interaction between MD and MO was observed (standardized β =−0.20, 95%CI −0.34 to −0.06, P=0.005), with post hoc analysis showing that males with combined exposure to MD and MO had lower thalamic volume compared to those with one or neither exposure (all Ps<0.05). In the hippocampus, an interaction between MO and infant sex was identified (standardized β =0.15, 95%CI 0.05 to 0.26, FDR corrected P=0.015), whereby MO (independent of MD) was associated with lower offspring hippocampal volume in females only (standardized β =−0.12, 95%CI −0.2 to −0.05, P=0.002). Conclusion and relevance: Our results suggest independent, interactive associations of intrauterine exposure to MD and MO with infant subcortical brain volumes, varying by sex. This has implications for future metabolic disorders, among other health risks.