Congenital hypothyroidism in Western Australia 1981-1998.

OBJECTIVE: Newborn screening for congenital hypothyroidism began in Western Australia in 1981. We describe the epidemiology, including trends over time. METHODOLOGY: Population-based registers and databases were used to identify cases of congenital hypothyroidism in 1981-1998 (n = 126), a random sample of controls (n = 1260), and descriptive data on cases and controls. The prevalence of congenital hypothyroidism per 10 000 live births was calculated, and a case-control analysis conducted. RESULTS: The prevalence of congenital hypothyroidism was 1.74 per 10 000 in the period 1981-1987, compared with 3.54 per 10 000 between 1988 and 1998. Infants identified with congenital hypothyroidism were significantly more likely to have other birth defects (particularly heart defects), be female, have a birthweight heavier than 4500 g, and be born either preterm or after 41 weeks gestation. No cases had cerebral palsy or intellectual disability. CONCLUSIONS: Population-based registers and linked databases can provide very useful information for evaluating screening programmes, and extending our knowledge of the epidemiology of congenital hypothyroidism.