[Physiology of ovulation and mode of action of contraceptive pills]

Follicular ovulation occurs at most 400 times in a woman's lifetime. This process involves enzymatic destruction of the cells surrounding the oocytes, called cumulus oophorus. The three different partners in order to obtain normal ovulation are the oocytes, the mature follicle containing adequate LH receptors and the hormones, especially progesterone and the preovulatory LH surge. Contraceptive pills available so far contain ethynyl estradiol, in order to regulate bleedings. The different progestins in the contraceptive pill exert an antigonadotropic effect and therefore inhibit follicular recruitment. As third generation progestins exert a stronger antigonadotropic effect than previous progestins, the dose of ethynyl estradiol has been lowered in the past 50 years.