Risk factors for transient and permanent congenital hypothyroidism: a population-based case-control study

Background: Congenital hypothyroidism (CH) is the most important cause of mental and physical retardation in newborns. The prevalence of CH has been reported high in East Azerbaijan province of Iran. However, the risk factors for CH are poorly understood. This study aimed to determine and compare risk factors for permanent and transient CH in East Azerbaijan, Iran.

Methods: A case-control study was conducted in the Iranian national screening program for CH. This study included 680 neonates: 340 neonates with confirmed CH and 340 matched healthy controls born at the same period and from the same residential area as the cases. Multiple logistic regression analyses were used to estimate the crude and adjusted odds ratios and 95% confidence intervals for the association between different risk factors and transient and permanent CH.

Results: Out of the 680 participants, 364 (53.53%) were male. Family history of CH (OR = 5.09, 95% CI: 1.66-15.63), neonatal jaundice (OR = 3.89, 95% CI: 2.36-6.43) and parental consanguineous relation (OR = 2.19, 95% CI: 1.51-3.17) were associated with an increased risk of permanent CH. Likewise, the use of Betadine in pregnancy (OR = 4.87, 95% CI: 1.45-16.28), family history of CH (OR = 5.98, 95% CI: 2.04-17.48), neonatal jaundice (OR = 2.81, 95% CI: 1.75-4.52), parental consanguineous relation (OR = 3.86, 95% CI: 1.92-5.74), and gestational age at birth (OR = 3.2, 95% CI: 1.90-5.41) were identified as risk factors for transient CH.

Conclusion: Family history, neonatal jaundice, gestational age at birth, and Betadine usage in pregnancy are associated with CH.