BACKGROUND: Preterm birth and young maternal age are known risk factors for infant and childhood mortality. There is limited knowledge of the impact of these risk factors in children born with major congenital anomalies (CAs), who have inherently higher risks of death compared with other children.

OBJECTIVES: To investigate the risk factors for mortality up to age 10 years in children born with specific major CAs.

METHODS: This population-based cohort study involved 150,198 livebirths from 1995 to 2014 in 13 European CA registries linked to mortality data. Cox proportional hazards models estimated the association of gestational age, maternal age and child's sex with death <1 year and 1-9 years for the whole cohort and by CA subgroup. Hazard ratios (HR) from each registry were pooled using multivariate meta-analysis.

RESULTS: Preterm birth had a dose-response association with mortality; compared with infants born at 37+ weeks gestation, those born at <28, 28-31 and 32-36 weeks had 14.88 (95% CI 12.57, 17.62), 8.39 (95% CI 7.16, 9.85) and 3.88 (95% CI 3.40, 4.43) times higher risk of death <1 year, respectively. The corresponding risks at 1-9 years were 4.99 (95% CI 2.94, 8.48), 3.09 (95% CI 2.28, 4.18) and 2.04 (95% CI 1.69, 2.46) times higher, respectively. Maternal age <20 years (versus 20-34 years) was a risk factor for death <1 year (HR 1.30, 95% CI 1.09, 1.54) and 1-9 years (HR 1.58, 95% CI 1.19, 2.10). Females had 1.22 (95% CI: 1.07, 1.39) times higher risk of death between 1 and 9 years than males.

CONCLUSION: Preterm birth was associated with considerably higher infant and childhood mortality in children with CAs, comparable to estimates reported elsewhere for the background population. Additional risk factors included young maternal age and female sex. Information on risk factors could benefit clinical care and guide counselling of parents following CA diagnoses.