<P> Ormeloxifene does not affect ovulation . It has been shown to increase the rate of blastocyst development and to increase the speed at which the blastocyst is moved from the fallopian tubes into the uterus . Ormeloxifene also suppresses proliferation and decidualization of the endometrium (the transformation of the endometrium in preparation for possible implantation of an embryo). While they are believed to prevent implantation rather than fertilization, exactly how these effects operate to prevent pregnancy is not understood . </P> <P> Pills--combined and progestogen - only--are the most common form of hormonal contraception . Worldwide, they account for 12% of contraceptive use . 21% of users of reversible contraceptives choose COCPs or POPs . Pills are especially popular in more developed countries, where they account for 25% of contraceptive use . </P> <P> Injectable hormonal contraceptives are also used by a significant portion--about 6%--of the world's contraceptive users . Other hormonal contraceptives are less common, accounting for less than 1% of contraceptive use . </P> <P> In 1921, Ludwig Haberlandt demonstrated a temporary hormonal contraception in a female rabbit by transplanting ovaries from a second, pregnant, animal . By the 1930s, scientists had isolated and determined the structure of the steroid hormones and found that high doses of androgens, estrogens, or progesterone inhibited ovulation . A number of economic, technological, and social obstacles had to be overcome before the development of the first hormonal contraceptive, the combined oral contraceptive pill (COCP). In 1957 Enovid, the first COCP, was approved in the United States for the treatment of menstrual disorders . In 1960, the U.S. Food and Drug Administration approved an application that allowed Enovid to be marketed as a contraceptive . </P>

Where do hormones in birth control come from