[Amenorrhoea following oral contraception. Pathophysiological problems (author's transl)].

In women with previously normal menstrual cycles the hypothalamus-pituitary-ovarian function returns to normal within one month after anovulatory steroids are discontinued, and although the follicular phase is prolonged, the ovulation mechanisms are restored within 3 to 4 weeks. Oral contraception by itself does not produce amenorrhoea, but it may mask possible disorders in the gonadotropic axis. Thus, in many cases post-contraceptive amenorrhoea indicates previous dysfunction of the anterior pituitary, which appears to involve lack of oestradiol positive feed-back and, to a greater extent, excessive negative feed-back. Following oestradiol administration, gonadotropic inhibition is abnormally prolonged beyond the 15th day. Cyclic activity is usually restored by clomiphene citrate. Post-contraceptive amenorrhoea is sometimes accompanied by galactorrhoea. Oestrogens facilitate prolactin secretion by producing hypertrophy and hyperplasia of pituitary prolactin-producing cells, but progestogens probably have an inhibitory effect on these cells, so that prolactin plasma levels are normal or slightly raised during treatment with anovulatory steroids. A pituitary microadenoma should be suspected in the presence of high prolactin levels, and oestrogenic treatments should be stopped. In all cases of amenorrhoea, whether or not they occur after oral contraception, the same etiological investigations should be carried out.