Impact of socioeconomic status and remoteness of residence on pregnancy outcome in major congenital heart disease: mediation analysis.

objectiveIncreased remoteness of residence (RoR) and lower socioeconomic status (SES) negatively impact the rate and gestational age (GA) at the diagnosis of major congenital heart disease (mCHD). We examined the direct and indirect relationships of RoR from a tertiary fetal cardiology center and Chan SES index with the rate of termination of pregnancy (TOP).

methodsWe conducted a retrospective population-based cohort study of all pregnancies with a prenatal diagnosis of mCHD in Alberta, Canada, from January 2008 to December 2021. Maternal RoR from the nearest tertiary fetal cardiology center and Chan SES index were primary exposures and GA at diagnosis of mCHD was examined as a potential mediator. The outcome was TOP. RoR, SES and GA at diagnosis were analyzed using structural equation modeling and mediation analysis, adjusting for maternal age, parity and presence of syndromic diagnosis.

resultsOf 1091 included pregnancies with mCHD and known pregnancy outcome, 203 (18.6%) ended in TOP. A lower rate of TOP was associated with diagnosis ≥ 22 weeks' gestation (47/532 (8.8%)) compared with diagnosis < 22 weeks (156/559 (27.9%)) (P < 0.001). There was a significant reduction in the rate of TOP among those with RoR ≥ 100 km (relative risk (RR), 0.94 (95% CI, 0.89-0.99); P = 0.022), and a trend towards an association between higher SES and increased likelihood of TOP (RR, 1.11 (95% CI, 1.00-1.22); P = 0.053), mediated by GA at diagnosis. There was no direct effect of RoR or SES on the rate of TOP. Diagnosis ≥ 22 weeks was associated with younger nulliparous (P = 0.018) and parous (P = 0.036) mothers, but not with maternal age overall. When stratified by the presence of a comorbid syndromic diagnosis, lower rates of TOP were indirectly associated with greater RoR and lower SES in fetal mCHD with syndromic diagnosis, mediated by GA at diagnosis (P = 0.057 and P = 0.02 respectively).

conclusionsThe parental decision to terminate pregnancy was related directly to GA at diagnosis of mCHD and related indirectly to greater RoR when mediated by GA at diagnosis. These findings should prompt further exploration of factors responsible for the later diagnosis of mCHD in those residing remotely. © 2026 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.