Effect of iodine supply on neonatal thyroid volume and TSH

A cross-sectional study was performed to prove the correlation between iodine intake and neonatal thyroid volume in a randomized group of 100 mother/newborn pairs. Thyroid volume and iodine excretion were measured by ultrasound and urinary iodine excretion, respectively. Iodine intake and, nutritional and smoking habits were estimated by questionnaire. In 89 mother/child-pairs the data were complete for all parameters and have been analyzed: 32 mothers substituted with iodine tablets, average dose 175 microg K-Iodide/day. Iodine excretion of prenatally iodine-substituted newborns increased by 62% whereas neonatal thyroid volume was reduced by 18% compared with the non-iodine-supplemented group. Smoker's newborns (n = 8) had a thyroid volume 20% larger than that of newborns of non-smokers. Neonatal TSH-screening values remained within normal limits.