Effects of combined oral contraceptive steroids on pituitary-ovarian function during the menstrual cycle of lactating women

The object of this study was to investigate the effects of combined oral contraceptives on pituitary-ovarian function during the menstrual cycle of lactating women whose prolactin levels were usually elevated. Five of six lactating women studied were considered to have the normal menstrual cycle which was comparable to the presumptive ovulatory cycle of non-puerperal women. The patterns of serum LH and FSH as well as estradiol and progesterone during the menstrual cycle of lactating women were, quantitatively and qualitatively, similar to those of nonpuerperal women. Prolactin levels, however, were elevated throughout the cycle of lactating women as compared with those of non-puerperal women. Treatment with combined oral contraceptive steroids abolished a midcycle surge of LH and decreased ovarian steroids during the menstrual cycle of lactating women. Serum prolactin levels were also decreased throughout the cycle treated with contraceptives in lactating women.