Congenital Hypothyroidism and its Related Factors in an Iranian Population: A Retrospective Study in Semnan (2011–2016)

Background: Congenital hypothyroidism (CH) is an important and preventable cause of intellectual disability. This study determined the incidence of CH and its related factors in Semnan city in Iran. Methods: All neonates born in Semnan from 2011 to 2016 who participated in a screening program for CH were evaluated to estimate the incidence of CH. In a nested case‑control study, all diagnosed CH cases were compared with a control group of healthy newborns. Statistical analysis used conditional logistic regression model with STATA‑14. Results: 106 out of 17,507 neonates born in Semnan during 2011–2016 were diagnosed with CH (6.05 cases per 1,000 live births). Maternal parity (odds ratio [OR] =1.78, P = 0.044), birth weight (OR = 0.29, P = 0.001), parental history of thyroid disease (OR = 3.43, P = 0.001), father’s education (OR = 0.71, P = 0.003), father’s occupation (nonworker) (OR = 2.97, P = 0.001), and the presence of other anomalies (OR = 4.14, P = 0.037) were related to the incidence of CH. Conclusions: The cumulative incidence of CH in Semnan was higher than in both the global and national statistics. Aside from well‑known medical determinants, some important social factors such as father’s occupation and education have a significant and independent relationship with occurrence of CH; rational attention should be given to them in health care programs to increase the effectiveness of preventative measures for CH.