Researchers from Boston University School of Medicine (BUSM) 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 150µg of supplemental daily iodine as recommended by the American Thyroid Association. The researchers' recommendation appears as a research letter in the February 26th issue of the New England Journal of Medicine.