"By the 1970s, however, there had been a sea tide of change in the evaluation of the safety of oral contraceptives since 1960. In 1962, before the British researchers established the statistical link with thrombosis, many physicians felt that the whole question of the pill’s side effects had been magnified, not by the actual danger, but by the concerns over thalidomide. No one disputed, however, that there was a need for more research to substantiate the concerns. By the time of the Nelson hearings, several large-scale studies of the pill and of thrombotic phenomena had been designed, and others were underway. The American Cancer Society, to cite a single example, initiated a seven-year study comparing 5000 pill users with 5000 nonusers. Experience with such large studies and interpretation of their results, as well as the new drug evaluation methods mandated by laws and regulations enacted in the wake of the thalidomide disaster, strengthened the entire new drug approval system worldwide."