The incidence of congenital hypothyroidism and its determinants from 2012 to 2014 in Shadegan, Iran: a case-control study

OBJECTIVES Congenital hypothyroidism (CH) is one of the major causes of preventable mental retardation in infants. The aim of this study was to determine the incidence of CH in Shadegan, Khuzestan Province, Iran from 2012 to 2014 and to identify the risk factors associated with CH. METHODS A total of 203 cases were confirmed from 2012 to 2014 in Shadegan, with 66, 86, and 51 patients reported in 2012, 2013, and 2014, respectively. A total of 3,900, 3,991, and 4,050 live births occurred in 2012, 2013, and 2014, respectively. The controls (n=657) were selected using a random number table, and a case-control study was carried out to determine the risk factors for neonatal CH, including demographic, environmental, and medical factors. RESULTS The incidence of CH was 17.0 per 1,000 live births in 2012, 21.5 per 1,000 live births in 2013, and 12.6 per 1,000 live births in 2014. This study showed that the likelihood of CH in children born to parents with a history of consanguineous marriage was 2.41 times greater than in children born to parents with no such history (odds ratio, 2.41; 95% confidence interval [CI], 1.65 to 3.53). This study also found that CH was 3.4 times more likely (95% CI, 2.29 to 5.20) in infants born in urban settings than in infants born in rural areas. CONCLUSIONS The incidence of CH in Shadegan from 2012 to 2014 was approximately 17 times greater than the expected incidence in Iran. CH was associated with a history of consanguineous marriage and urbanization.