I don't think they do it for contraception.
I have had a family member who had gone through this, so I'm a little grouchy on the issue.
I highly doubt that people are subjecting their daughters to this barbarity for the purpose of contraception, thought it seems like childbirth after the most extreme form would be so torturous it would discourage women from having more than one child -- if they survived it.
The only way to overcome such culturally ingrained barbarity is through education. Remember a while ago when African men with AIDS thought they could cure themselves by having sex with a virgin? I don't know if the campaign was successful, but they attacked that with education.
Personally, I can't imagine letting anyone cause my child pain for any reason, especially for social acceptance. But then, I don't depend on my neighbors for survival and I myself was not subjected to such barbarity.
From osso's link--
Reason for Female Genital Mutilation:
psychosexual reasons: reduction or elimination of the sensitive tissue of the outer genitalia, particularly the clitoris, in order to attenuate sexual desire in the female, maintain chastity and virginity before marriage and fidelity during marriage, and
increase male sexual pleasure;
sociological reasons: identification with the cultural heritage, initiation of girls into womanhood, social integration and the maintenance of social cohesion;
hygiene and aesthetic reasons: the external female genitalia are considered dirty and unsightly and are to be removed to promote hygiene and provide aesthetic appeal;
myths: enhancement of fertility and promotion of child survival;
religious reasons: Some Muslim communities, however, practise FGM in the belief that it is demanded by the Islamic faith. The practice, however, predates Islam.
Prevalence and distribution of FGM
Most of the girls and women who have undergone genital mutilation live in 28 African countries, although some live in Asia and the Middle East. They are also increasingly found in Europe, Australia, Canada and the USA, primarily among immigrants from these countries.
Today, the number of girls and women who have been undergone female genital mutilation is estimated at between 100 and 140 million. It is estimated that each year, a further 2 million girls are at risk of undergoing FGM.
This is so incredibly sad.