Getting to the heart of the matter: epidemiology of cyanotic heart defects.

Congenital heart defects (CHDs) are the most common type of birth defect, making significant contributions to infant morbidity and mortality, but not all CHDs contribute equally to such outcomes. Although cyanotic CHDs constitute some of the most serious CHDs, its epidemiology is poorly understood. We present a comprehensive systematic review of the literature on the epidemiology of cyanotic CHD, with emphasis on the most current knowledge on identified risk/etiologic factors. Literature for this review was identified by searching the PubMed database from the National Center for Biotechnology Information at the US National Library of Medicine as well as bibliographies of identified papers. The 100 reports that contributed to this review describe risk factors such as infant sex, race, and ethnicity, environmental exposures, and maternal and paternal age. Several studies reported differences in prevalence rates by race and ethnicity and elevated sex ratios, and they identified some risk factors, including advanced maternal age. Investigators have made significant progress in the effort to describe the etiology of cyanotic CHDs, but discrepancies, such as the variation in prevalence rates by race and ethnicity and the impact of environmental exposures, still need to be addressed.