Background: Congenital heart defects (CHDs) are the most common birth defects, affecting approximately 1% of births annually in the United States. Critical congenital heart defects (CCHDs), comprising approximately 25% of CHDs, are associated with substantial morbidity and mortality. Elevated risk of CCHDs has been suggested among pregnancies occurring at moderately high altitude (4,921–8,202 feet). Colorado, the highest elevation state in the US, has an average elevation of 6,800 feet. We sought to determine whether Colorado has a higher prevalence of CCHDs at birth compared with national estimates.
Methods: Data from the statewide birth defects surveillance system, Colorado Responds to Children with Special Healthcare Needs (CRCSN), were analyzed for the years 2016–2021 to identify CCHD cases using International Classification of Diseases, Ninth and Tenth Revision (ICD-9 and ICD-10) diagnostic codes recommended by the National Birth Defects Prevention Network (NBDPN). National comparison data were obtained from population-based estimates derived from 13 U.S. surveillance programs for 2016–2020. Prevalence estimates of CCHDs, overall and by defect category, were calculated as cases per 100,000 live births.
Results: Case-level data were available for 381,168 live births in Colorado between 2016 and 2021. A total of 1,025 CCHD cases were identified, corresponding to a prevalence of 26.9 per 100,000 live births. Colorado has higher prevalence estimates for several CCHD subtypes compared with national estimates, including coarctation of the aorta (10.4 vs. 5.8 per 100,000), hypoplastic left heart syndrome (5.2 vs. 2.6 per 100,000), interrupted aortic arch (4.0 vs. 1.0 per 100,000), pulmonary valve atresia (2.8 vs. 1.5 per 100,000), and single ventricle defects (2.5 vs. 0.7 per 100,000).
Implications: These findings raise concern that Colorado’s high-altitude environment may contribute to increased prevalence of selected CCHDs. We will discuss strategies to strengthen surveillance infrastructure to improve prevalence estimation and support early detection and prevention efforts.
