Most contraceptive methods are designed by men for women, partly as a result of the traditional male-female relationship and partly due to the natural consequences of no birth control. There is so far no method which is 100% satisfactory either in controlling pregnancy or in its lack of side-effects. While the consideration of loss of libido is a strong force in withholding the marketing of male contraceptives, this has never been considered as a valid reason against the use of female contraceptives. Women are also expected to tolerate the unpleasant physical side-effects of the pill or the IUD. Discrimination in research promotion and usage of different methods also exists between rich and poor women, and between women of different races.