Risk Factors of Congenital Hypothyroidism in Israel

Background: Congenital hypothyroidism (CH) is the most common preventable cause of mental retardation and delayed growth in children. Several prenatal and environmental factors might be associated with the disease. Objectives: To determine the prevalence and risk factors of permanent CH and transient congenital hypothyroidism (TCH) in Israel. Methods: We conducted a retrospective analysis of the Israeli national newborn screening program database from 2011 to 2015. Chi-square and logistic regression were used to assess the association of the demographic and gestational factors with the CH and TCH. Results: Of the 889,033 live births screened between 2011 and 2015,860 were diagnosed with CH (9.76 per 10,000 live births) and 298 with TCH (3.35 per 10,000 live births). In multivariate analyses, CH was positively associated with female sex, gestational ages < 38 or > 39 weeks, birth weight < 3000 grams, and winter birth. A decreased risk of TCH was detected in Arabs and neonates from high socioeconomic areas. An increased risk was independently associated with gestational ages < 38 weeks, low birth weight, and winter birth. Conclusions: Several demographic, gestational, and geographical factors are associated with the development of CH and TCH. Future studies are needed to further investigate the pathogenesis in Israel.