Pregestational diabetes mediates the association between maternal obesity and the risk of congenital heart defects

AIMS/INTRODUCTION: We aimed to explore whether the association between obesity and congenital heart defects (CHDs) can be mediated by maternal pregestational diabetes (PGDM). MATERIALS AND METHODS: We included 53,708 mother‐infant pairs with deliveries between 2017 and 2019 from the Birth Cohort in Shenzhen. Mothers were categorized into four groups: the underweight group (body mass index [BMI] <18.5), normal weight group (18.5 ≤ BMI < 24), overweight group (24 ≤ BMI < 28) and obesity group (BMI ≥28). Multivariable logistic regression models were used to evaluate the association between BMI and CHDs. Mediation analysis was used to confirm the effect of PGDM on the association between maternal obesity and CHDs. RESULTS: The proportion of obese individuals in the Birth Cohort in Shenzhen was 2.11%. Overall, 372 (0.69%) infants were diagnosed with CHDs. Maternal obesity was associated with an increased risk of CHDs (odds ratio 1.97, 95% confidence interval 1.14–3.41). The mediation effect of PGDM on the association between maternal obesity and CHDs was significant (odds ratio 1.18, 95% confidence interval 1.06–1.32). The estimated mediation proportion was 24.83%. CONCLUSIONS: Maternal obesity was associated with increased risk for CHDs, and PGDM partially mediated the association between maternal obesity and CHDs.