Hypoplastic left heart syndrome

Rare, genetic, and present at birth, Children and teens. Also called: HLHS.

How common is Hypoplastic left heart syndrome in the US?

Birth prevalence of hypoplastic left heart syndrome, 2.6 cases per 10,000 live births (95% CI 2.4–2.7): 2.6 (Live births in 11 population-based U.S. birth-defects surveillance programs that ascertained all pregnancy outcomes and used medical-record abstraction; pooled surveillance covered 4,231,701 live births (about 23% of U.S. births); United States surveillance programs contributing to the 2018–2022 national-estimates analysis, 2018-2022). Source: Centers for Disease Control and Prevention / National Birth Defects Prevention Network, 2026. Label: VERIFIED.

• 2.6 Birth prevalence of hypoplastic left heart syndrome, 2.6 cases per 10,000 live births (95% CI 2.4–2.7). Out of: Live births in 11 population-based U.S. birth-defects surveillance programs that ascertained all pregnancy outcomes and used medical-record abstraction; pooled surveillance covered 4,231,701 live births (about 23% of U.S. births). Where: United States surveillance programs contributing to the 2018–2022 national-estimates analysis. When: 2018-2022. Label: VERIFIED.

  Hypoplastic left heart syndrome — 2.6

  Source: Prevalence of Selected Birth Defects from Population-Based Birth Defects Surveillance Programs in the United States, 2018–2022 Centers for Disease Control and Prevention / National Birth Defects Prevention Network, 2026.

Each figure measures something different. Do not compare them with each other or with other conditions.

Medical codes

• ICD-10-CM FY2026: Q23.4 Hypoplastic left heart syndrome (exact)

Research activity

As of 2026-09-24: 70 registered studies on ClinicalTrials.gov (search Hypoplastic Left Heart Syndrome) and 1,025 PubMed records, 2021 to 2025. A count of records is not how common or serious the condition is.

Population information, not medical advice. Methodology · Known limitations