Female circumcision has been used in the United States as a method of increasing female sexual response to marital heterosexual sex since the late nineteenth century. By removing the clitoral foreskin, some doctors and lay people thought the clitoris would be more exposed to the penis during penetrative intercourse and would thus receive direct stimulation from the penis, thereby increasing female orgasmic potential.
http://onlinelibrary.wiley.com/doi/10.1002/97…ehs089/abstract