Prenatal computed tomography (CT) and risk of congenital heart disease and cerebral palsy: A nationwide mother–child paired cohort study

Although the use of computed tomography (CT) imaging during pregnancy is increasing, the decision to use CT imaging remains challenging due to the conflicting considerations of the potential risks of fetal radiation and the medical benefits to the mother, with inconsistent evidence on offspring outcomes. Nationwide retrospective cohort study based on the Korean National Health Insurance Service database, including 5,457,153 live births between 2005 and 2019. After 1:4 propensity score matching by maternal characteristics and diagnosis at the same gestational age, 13,307 CT-exposed and 42,946 unexposed pregnancies were included. CT exposure during pregnancy was identified using claims data from the last menstrual period to delivery. Estimated fetal radiation exposure was approximated based on anatomical scan location and categorized into lower and higher exposure groups, corresponding to non-abdominopelvic and abdominopelvic CT, respectively. Outcomes included major congenital malformations, congenital heart disease, and cerebral palsy identified using ICD-10 codes. Cox and logistic regression models were used, accounting for clustering by mother. Among CT-exposed pregnancies, 37.0% occurred within 14 days post-last menstrual period (LMP), and no increased risk of malformations or cerebral palsy was observed in this group. However, CT exposure during the first trimester was associated with a higher risk of major congenital malformations (Odds ratio (OR) 1.14, 95% confidence interval (CI) 1.02–1.30) and cerebral palsy (Hazard ratio (HR) 2.10, 95% CI 1.48–2.97). In a sensitivity analysis, non-abdominopelvic CT was associated with congenital heart disease (OR 1.23, 95% CI 1.03–1.47), but not with cerebral palsy, while abdominopelvic CT was associated with both congenital heart disease (OR 1.47, 95% CI 1.12–1.92) and cerebral palsy (HR 2.04, 95% CI 1.08–3.84). Even diagnostic-level CT radiation exposure during pregnancy may be associated with increased risks of congenital and neurodevelopmental disorders. Current radiation safety thresholds based solely on carcinogenic risk may underestimate fetal developmental vulnerability. However, this study has limitations, particularly the potential for residual confounding related to clinical acuity at presentation, which may not be fully addressed despite restriction to similar diagnostic indications and extensive propensity score matching.