Prevalence and risk factors for congenital diaphragmatic hernia: A global view

Purpose: To determine the global prevalence for congenital diaphragmatic hernia (CDH) and identify CDH-related risk factors. Methods: Using a defined strategy, a systematic review of the literature was conducted according to PRISMA guidelines, searching for population-based epidemiological studies to evaluate the prevalence of CDH globally and per country. Studies containing overlapping populations or timeframes were excluded. CDH-related risk factors were calculated by meta-analysis using RevMan5.3 and expressed as risk ratio and 95% confidence interval. Results: Prevalence: Of 8230 abstracts screened, 30 full-text articles published between 1980 and 2019 were included. The overall prevalence of CDH was 2.3 in 10,000 births (16,710 CDH babies in 73,663,758 livebirths). Risk factors: From 9 studies we found that male sex [RR 1.38 (1.05–1.80), p = 0.02] and maternal age > 35 years [RR 1.69 (1.26–2.25), p = 0.0004] were associated with CDH. Conversely, maternal black ethnicity resulted as a protective factor [RR 0.82 (0.77–0.89, p < 0.00001]. Conclusion: This study reveals that there is a worldwide paucity of population-based studies, and those studies that report on prevalence and risk factors come from a small number of countries. The prevalence of CDH varies within and across geographical world regions. The main risk factors for CDH identified are male sex and older maternal age. More epidemiological studies, involving more world regions, are needed to identify possible strategies to help strengthen our understanding of the risk factors, provide clinicians with the tools necessary for prenatal and postnatal counseling, and inform policy makers on how to strategize CDH care in different parts of the world. Type of study: Systematic review and meta-analysis. Level of evidence: Level III.