Objectives: To evaluate the incidence, risk factors and neonatal outcomes associated with a congenital diaphragmatic hernia (CDH).

Study design: We conducted a population-based cohort study using the CDC’s Linked Birth-Infant Death and Fetal Death data files on all births and foetal deaths in USA between 1995 and 2002. We estimated the yearly incidence of CDH and measured its adjusted effect on various outcomes using unconditional logistic regression analysis.

Results: About 32 145 448 births during the 8-year study period met the study’s inclusion criteria. The incidence of CDH was 1.93/10 000 births. Risk factors for the development of CDH included foetal male gender [OR 1.12, 95% CI: 1.06, 1.17], maternal age beyond 40 [OR 1.51, 95% CI: 1.26, 1.80], Caucasian ethnicity [OR 1.15, 95% CI: 1.10, 1.21], smoking [OR 1.34, 95% CI: 1.22, 1.46] and alcohol use during pregnancy [OR 1.37, 95% CI: 1.05, 1.79]. As compared to foetuses with no CDH, foetuses with CDH were at an increased risk of preterm birth [OR 2.90, 95% CI: 2.72, 3.11], intrauterine growth restriction [OR 3.84, 95% CI: 3.51, 4.18], stillbirth [OR 9.65, 95% CI: 8.20, 11.37] and overall infant death [OR: 94.80, 95% CI: 88.78, 101.23]. The 1-year mortality was 45.89%.

Conclusion: Congenital diaphragmatic hernia is strongly associated with an increased risk of adverse pregnancy, foetal and neonatal outcomes. These findings may be helpful in counselling pregnancies affected by CDH, and may aid in the understanding of the burden of this condition at the public health level.