- Worldwide: 1 in 3,000–4,000 births; in North America, 1 in 3,700
- Male/Female ratio is 1:2–1:3.
- 80% dysgenesis or agenesis; 20% dyshormonogenesis
- Racial differences: Prevalence in black infants ~1/3 that in whites
- Higher prevalence of congenital hypothyroidism in low–birth-weight (>2,000 g) and macrosomic (≥4,500 g) babies