1696 Risk of congenital diaphragmatic hernia at early and advanced maternal age: results from a population-based cohort study in England

BackgroundDespite advances in clinical management, congenital diaphragmatic hernia (CDH) is still associated with high rates of mortality and morbidity in the UK. Population-based studies examining the epidemiology of CDH in the UK are needed to understand which factors are associated with the condition and to inform preventative interventions. A major determinant of outcomes among infants with CDH is the presence of associated anomalies. Although maternal age is a known proxy of sociodemographic, behavioural and biological risk factors for adverse pregnancy outcomes, its relationship with CDH in the UK and how this might vary among those with additional anomalies is not known.ObjectivesTo examine the relationship between maternal age and CDH, including in the absence and presence of additional anomalies which may suggest syndromic conditions.MethodsWe analysed all live-born singletons delivered in NHS England hospitals between 2002 and 2018. De-identified hospital admission and mortality data were searched up until the first birthday to identify infants with a CDH diagnosis, related repair or related death. CDH was further classified as isolated (no additional malformations) or complex (additional malformations beyond the digestive or respiratory systems). The association between maternal age (categorized as <20, 20–24, 25–29, 30–34 and ≥40 years) and any CDH, isolated CDH and complex CDH was estimated using logistic regression that also included birth period, ethnicity, deprivation, and region of maternal residence at delivery.ResultsWe identified 2,289 infants with CDH among 7.7 million live-births (3.0/10,000 live-births; 95% CI, 2.8–3.1); 49% were complex cases. Maternal ages of 35–39 and ≥40 years were associated with a 17% and 36% increased risk of any CDH, respectively, compared to the reference age of 25–29 years. There was weak evidence of increased risk for mothers <20 years. Isolated CDH was not associated with any age group. The estimated risk of complex CDH was increased for mothers aged <20, 35–39 and ≥40 years, by 33%, 26% and 63%, respectively, compared to the reference age of 25–29 years.ConclusionsEarly and advanced maternal age were associated with complex CDH even after adjustment for other demographic factors, but these associations were not replicated for isolated CDH. While further work is needed to understand the underlying mechanisms, this study suggests that maternal age could be a useful indicator of increased risk of complex CDH.