[Repercussion of the application of povidone-iodine to the umbilical stump on thyroid function of the neonate at term].

We have studied blood TSH and T4 5-7 days after birth in 356-healthy newborns whose umbilical stump had been treated with 10% povidone-iodine. The prevalence of high TSH levels (above 20 microU/ml) was higher in this group than in the general population (3.09% vs 0.417%, p less than 0.001), and so was the rate of transient hypothyroidism (2.73% vs 0.25%, p less than 0.001). Both differences were related to the number of applications of iodine given. All children were found to be normal at retesting one week later. This study adds new evidence on the high vulnerability of newborn thyroid to small iodine doses and further discourages the use of povidone-iodine for the care of umbilical stump.