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.