Congenital hypothyroidism: increased risk of neonatal morbidity results in delayed treatment.

In a population-based screen of 617,913 infants, primary congenital hypothyroidism (CH) was confirmed in 100 children. 32 of the 100 infants with CH had an additional defect or complication. In the group with CH the rates of congenital heart disease, non-cardiac malformations, respiratory distress syndrome, and death were higher than in the general population of the same age. Black infants were less likely than whites to have CH, but were at twice the risk of additional impairment. Infants with CH who had an additional complication were screened (12.7 vs 4.8 days) and treated (32.4 vs 19.7 days) significantly later than those infants with isolated CH. Congenital malformations and neonatal complications should not be reasons for deferring screening for CH.