Assessment of subsequent fecundability in parents of children with congenital abnormalities: a matched cohort study from China

The birth and diagnosis of a child with congenital abnormalities can alter parental reproductive patterns, yet its association with subsequent fecundability remains insufficiently explored. We conducted a government-supported matched cohort study in China to evaluate this association and assess whether it varies by the severity of the child's condition and parental characteristics. A total of 2448 couples from the National Free Pre-conception Check-up Project between 2012 and 2018 attempting to conceive again were included: 612 exposed couples with children affected by congenital abnormalities and 1836 non-exposed couples with unaffected children and no adverse pregnancy history. Participants were followed via telephone every 3 months for one year to track pregnancy outcomes. Cox proportional hazards models with a shared frailty were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for fecundability. Overall, exposed couples demonstrated a 28% higher fecundability than non-exposed couples (HR 1.28, 95% CI: 1.10-1.49). This association was primarily observed among parents with "healthy" characteristics and those whose children had single-system/body-part congenital abnormalities (HR 1.27, 95% CI: 1.09-1.48). These findings highlight the importance of integrated fertility counseling, prenatal screening, and psychological support for families seeking subsequent pregnancies after the birth of a child with congenital abnormalities.