What drives outcomes in infants of mothers with congenital heart disease? A mediation analysis

Objective: Infants of mothers with adult congenital heart disease (ACHD) are at increased risk for adverse pregnancy and neonatal outcomes. We aim to identify mediators in the relationship between ACHD and pregnancy and infant outcomes. Study design: Case-control study using linked maternal and infant hospital records. Structural equation modeling was performed to assess for potential mediators of pregnancy and infant outcomes. Result: We showed an increased risk of multiple adverse infant and pregnancy outcomes among infants born to mothers with ACHD. Maternal placental syndrome and congestive heart failure were mediators of prematurity. Prematurity and critical congenital heart disease in the infant were mediators of infant outcomes. However, the direct effect of ACHD on outcomes beyond that explained by these mediators remained significant. Conclusion: While significant mediators of infant and pregnancy outcomes were identified, there was a large direct effect of maternal ACHD. Further studies should aim to identify more factors that explain these infants’ vulnerability.