Increase in congenital hypothyroidism in New York State and in the United States.

Mandated screening of newborns for congenital hypothyroidism (CH) in NYS was initiated in l978. Currently, every newborn screening program in the U.S. includes CH in its panel. Between 1978 and 2005, 7.4 million newborns were screened for CH in NYS. In NYS, between 1978 and 2005, the incidence of CH has increased by 138%. Nationwide (excluding NYS data), with nearly 58 million infants screened between 1987 and 2002, the incidence has increased 73% between 1987 and 2002. These data and possible reasons for the increases are discussed, though no definitive causes are identified.