Aim: OF THE STUDY: Congenital Diaphragmatic Hernia (CDH) is associated with high mortality linked to lung hypoplasia, pulmonary hypertension and associated major anomalies. Sex differences impacting on outcome metrics remain largely unexplored. Male and female CDH patients are examined in this study with regard prenatal and postnatal variables including health outcome(s) morbidity.

Methods: A systematic review and meta-analysis was conducted with PRISMA guidelines, searching Cochrane, PubMed, Embase, Web of Science, and Medline databases. Studies comparing male and female CDH patients (0-18 years) were included. Random-effects meta-analyses was undertaken to report outcomes between sexes.

Main results: Sixteen studies comprising 14,109 patients (8240 males, 5859 females) were analysed. Meta-analysis showed a non-significant trend towards higher mortality in females (28% vs 24%; RR = 0.89, 95% CI [0.79, 1.01], p = 0.07). No differences were recorded in CDH defect laterality (right: RR = 0.97, left RR = 1.01, bilateral: RR = 0.74). The comparison between the groups showed that females had significantly higher rates of cardiac anomalies (22.9% vs 19.8%; p = 0.01) and chromosomal disorders (9% vs 7%; p = 0.003). Pulmonary hypertension was documented significantly more often in males than females in one study (70% vs 60%, p < 0.00001).. Clinical parameters analysed varied minimally-prenatal detection (female 74% vs male 71%), rate(s) of surgical repair (female 83% vs male 85%), and patch use (female 44% vs male 45%).

Conclusions: This study demonstrates a non-significant trend towards higher mortality (28% vs 24%) in female vs male CDH patients with notably a significantly higher incidence (%) of cardiac and chromosomal anomalies in girls. Males had significantly more pulmonary hypertension in one contributing study. While most clinical parameters studied were similarly equivalent between the sexes, female CDH patients may yet represent a 'high-risk 'group phenotype particularly for mortality and co-morbidities. Further research is crucially needed to better understand these sex-specific differences and their potential clinical implications.