Massachusetts began the original newborn screening program back in 1963 with a test for PKU. Though few babies were found to have the condition, the benefit of an early diagnosis was so great that other states soon instituted screening programs. Once they'd adopted the practice, states expanded their scope and began testing for more conditions. Ten years ago, 46 states were screening for just six conditions; now all 50 states and the District of Columbia routinely screen newborns for at least 30 genetic conditions, with some states testing for nearly twice that number.
Though each state runs its own program, they all begin by collecting a blood spot from the heel of a newborn infant. The sample is analyzed; results are returned. Commonly, the screening program is first mentioned when a mother has checked into the hospital for delivery, and, generally, the programs are mandatory under state law.