Background — A twofold increase in the prevalence of congenital heart defects (CHDs) has been reported since the early 1970s with higher rates among children from low socioeconomic status (SES). This increase and the observed SES gap are postulated to be reflective of higher ascertainment, especially increased use of ultrasound and echography. The purpose of this study was to examine if trends over time in the prevalence of CHD were the same for high and low SES groups.

Methods — Using the child's health number as a unique identifier and through record linkage, children born in Ontario between 1994 and 2007 were followed for the diagnosis of CHD. Using postal codes and census information, SES quintiles were assigned to each child. The researchers used adjusted rates and used multivariate models to compare trends in the prevalence rate among children born in different SES groups.

Results — Children born in low SES areas (23% of all births) had significantly higher rates of CHDs (rate ratio = 1.20; 95% confidence interval [CI] = 1.15-1.24). While prevalence of nonsevere CHDs declined in all SES groups since 2000, severe CHDs, especially atrial septal defects were on the rise during the study period.

Discussion — It is assumed that increased ascertainment is responsible for observed increase in the prevalence of CHD, especially minor defects. While the trend and pattern over time changed for severe and nonsevere CHDs, the SES gap remained consistent during the study period. Our results indicate that even free and universal access to a health care system does not eliminate the SES gap observed in the prevalence of CHD.