Prenatal Vitamins Should Contain Only Potassium Iodide, Not Other Sources Of Iodine, Scientists Urge (Science Daily) Researchers are strongly encouraging prenatal vitamin manufacturers to use only potassium iodide and not other sources of iodine in their products. According to the researchers, potassium iodide is the best way to ensure that prenatal vitamins given to expectant mothers receive 150ug of supplemental daily iodine as recommended by the American Thyroid Association. [News Source]