[The effect of low dose gestagens on the hypothalamic-pituitary-ovarian axis].

The contraceptive effect of continuous treatment with low dose progestogens (minipill) has been attributed mainly to alterations of the cervical mucus and the endometrium. This study was undertaken to investigate the effect of low dose progestogens on hypothalamic-pituitary-ovarian function. Plasma concentrations of follicle stimulating hormone (FSH), luteininzing hormone (LH), estradiol-17 beta (E-2) and Progesterone were measured daily during apparently ovulatory menstrual cycles and during treatment cycles with different low dose progestogens. From the results obtained it was concluded that the minipill has a clear-cut effect on the LH/FSH peak at midcycle and on corpus luteum function. A cyclic secretion of E-2 is maintained in the majority of cases. In a few treatment cycles however, follicular maturation was suppressed as indicated by low E-2 concentrations. It was concluded that the minipill exerts a profound effect at the central and ovarian level which contributes to its satisfactory contraceptive efficacy.