Association between maternal marginalization and infants born with congenital heart disease in Ontario Canada

BACKGROUND: This study aims to evaluate the impact of socioeconomic status (SES) on the risk of congenital heart disease (CHD) since previous studies have yielded inconsistent results. METHODS: We conducted a population-based retrospective cohort study, including all singleton live and still births in Ontario hospitals from April 1, 2012, to March 31, 2018. We used linked records from the Better Outcomes Registry & Network Information System, the Canadian Institute for Health Information databases, and the Ontario Marginalization Index (ON_Marg). ON_Marg was estimated at a dissemination area level using Canadian Census 2016 data and categorized into quintiles. Multivariable logistic regression models were performed to examine the relationships between four ON_Marg indices (material deprivation, dependency, ethnic concentration, residential instability), as proxies for maternal SES and the risk of infant CHD. We adjusted for maternal age at birth, assisted reproductive technology, obesity, pre-existing health conditions, substance use during pregnancy, mental health conditions before and during pregnancy, rural residence, and infant's sex in the analysis. RESULTS: Among the cohort of 776,799 singletons, 9,359 infants had a diagnosis of CHD. Of those, 3,069 were severe CHD and 493 cases were single ventricle CHD. The prevalence of all infant CHD types was higher for males relative to females. Compared to mothers living in neighbourhoods with the lowest material deprivation, mothers with highest material deprivation had a 27% (adjusted OR = 1.27; 95% CI: 1.18-1.37) higher odds of having an infant diagnosed with CHD. Mothers living in neighbourhoods with the highest minority ethnic and immigrant concentration tend to have infants with 11% lower odds of CHD (adjusted OR = 0.89; 95% CI: 0.82-0.97) as compared to those living in the least ethnically diverse communities. Maternal dependency and residential stability quintiles were not significantly associated with the risk of CHD. CONCLUSION: Higher maternal material deprivation was associated with increasing odds of infant CHD, whereas neighbourhood minority ethnic concentration was inversely associated with the odds of infant CHD. Our study further confirms that poverty is associated with CHD development. Future investigations might focus on the causal pathways between social deprivation, immigrant status, ethnicity, and the risk of infant CHD.