Effect of in utero exposure of iodinated intravenous contrast on neonatal thyroid function

PURPOSE: Administration of radioactive iodine to a pregnant woman for thyroid ablation has been shown to affect neonatal thyroid levels. Thus, there is a theoretical risk in affecting a neonate's thyroid level upon birth with prior administration of intravenous contrast containing iodine to a pregnant woman during a computed tomographic scan. However, there is no literature to support this theoretical risk. This study attempted to determine if there is any effect on a newborn's thyroid levels after exposure to this type of contrast material in utero. MATERIALS AND METHODS: The medical charts of 96 pregnant women during the years 2004 through 2009 on whom computed tomographic scans were performed were reviewed. A total of 29 charts were excluded secondary to missing neonatal records, missed abortions, and intrauterine fetal demise. The rest were subdivided into those who received intravenous (IV) ± oral contrast material and those who did not. The medical records of the newborns of these patients were also reviewed. The subject group consisted of 61 pregnant women who received IV ± oral contrast and their 64 neonates. The control group consisted of 6 pregnant patients who did not receive IV contrast and their 6 neonates. RESULTS: Of the 64 neonates in the subject group, only one neonate was found to have a low thyroxine level with a normal thyroid stimulating hormone level. This infant was severely premature, being born at the 25th week of gestation, and developed respiratory distress syndrome and sepsis, which were potential confounding factors. All of the 6 neonates in the control group had normal thyroid levels. CONCLUSION: This study concludes that there is no significant adverse clinical risk of thyroid function abnormalities to the fetus after IV iodinated contrast material to their mothers.