Incidence of Congenital Diaphragmatic Hernia in Canada: Time Trends and Analysis by Location, Maternal Age, and Sex

Introduction: Congenital diaphragmatic hernia (CDH) is a birth defect of unknown etiology, whose epidemiology has not been extensively studied in Canada. The aim of our study was to report the incidence of CDH in Canada and its provinces/territories by year and putative risk factors. Methods: Aggregate population health data were obtained from the Government of Canada's Congenital Anomalies report on CDH, which utilized the Canadian Institute of Health Information Discharge Abstract Database from 2006 to 2020, as well as the MED-ÉCHO database for Quebec from 2008 to 2020. We calculated incidence per 10,000 births with 95 % confidence intervals (CI) per province, year, maternal age, and infant sex (Statistics Canada) and used Poisson regression and Chi- squared tests to analyze differences in incidence rate ratios (IRR) and proportions over time, province, age, and sex. Results: The incidence of CDH in Canada during the study period was 2.71/10,000 births. Males comprised a larger proportion of CDH cases (IRR 1.32, 95 % CI 1.19–1.46). There was no change in incidence over time (p = 0.7). Women aged ≥40 at the time of delivery demonstrated an increased incidence of CDH compared to mothers aged 25–29 (IRR 1.68, 95 % CI 1.20–2.30). Compared to Ontario (most populated province in Canada), the incidence of CDH was higher in Manitoba (IRR 1.33, 95 % CI 1.05–1.65), but was not different in other provinces. Discussion: The incidence of CDH in Canada is comparable to that reported by European and North American population-based registries. Incidence was found to vary significantly by geographic region, maternal age, and fetal sex. Type of study: Cross-sectional population study. Level of evidence: IV.