Risk factors for congenital hypothyroidism in Fars Province, Iran, 2003-2006

The prevalence of congenital hypothyroidism (CH), one of the main causes of preventable mental handicap in neonates, is much higher in Iran than the global average.The objective of this study was to identify risk factors for congenital hypothyroidism (CH) by using the screening program in Fars Province, Iran, during the period 2003-2006. Methods and Materials: A case-control study was carried out, the samples being 126 cases and 401 controls. The neonates were those born between 2003 and 2006, under coverage of the National Congenital Hypothyroidism Program. The data were analyzed using the univariate and multivariate analysis tests. An increased risk for CH was detected in infants with consanguine parents, by a multivariate analysis test (odds ratio (OR) = 2.9, 95% confidence interval (CI):1.8-4.8). The test also confirmed previously reported statistically significant associations with additional birth defects OR = 2.2 (1-4.6), birth defects in first-degree relatives OR = 4.7 (1.6-4.8), female gender OR = 1.9 (1.1-3), and twin births. Although not significant, an increased risk for CH was observed among infants with gestational age<30 weeks (preterm delivery) (OR = 1.7(0.9-1.3)). This study identified risk factors contributing to the etiology of CH. In particular, our results suggest a multifactorial origin of CH, in which both genetic and environmental factors play a role.