Severe hypothyroidism developed in a 4-year-old girl whose mother received four courses of sodium iodide I 131 therapy during pregnancy. Mechanisms of fetal thyroid damage by radioactive iodine include placental transfer, possible concentration of radio-active iodine by the fetal thyroid gland, and possible ablation or partial damage of the fetal thyroid gland by radioactive iodine. Any infant whose mother received131 I during pregnancy should receive careful long-term follow-up.
Green HG, Gareis FJ, Shepard TH, Kelley VC. Cretinism Associated With Maternal Sodium Iodide I 131 Therapy During Pregnancy. Am J Dis Child. 1971;122(3):247–249. doi:10.1001/archpedi.1971.02110030105016