"Once marketed in the United States and Britain, Enovid/Enavid was freely available to women whose doctors would prescribe it, either as a treatment for infertility or for menstrual disorders. Medical doctors in both countries could then, as they can now, prescribe drugs for purposes other than those approved because neither country has ever sought to regulate the practice of medicine. The fact that so many women may (or may not) have had access to Enocid/Enavid years before it was formally approved by FDA as a contraceptive makes any discussion about the approval of the pill which centers upon numbers very difficult. The most commonly cited figure is that by 1959 more than 500,000 women were taking the drug for menstrual disorders in the United States."