THE EFFECTS OF PROGESTERONE AND PROGESTINS ON ENDOMETRIAL PROLIFERATION

A total of 99 premenopausal and 27 postmenopausal women were evaluated to determine the quantity of glandular proliferation resulting from p rogestin inhibition of estrogen-primed subjects and of subjects withou t hormonal stimulation. Endometrial glandular proliferation rates were determined by using mitosis counts, proliferation-cell nuclear antige n (PCNA), and nuclear cyclin (MIB1) immunocytological staining. The en dometria of normally cycling premenopausal women, of women who receive d a synthetic progestin, and of untreated postmenopausal women were st udied. In unheated normally cycling premenopausal women, the prolifera tion of the glandular epithelium was increased during the follicular p hase and decreased during the luteal phase. Premenopausal women receiv ing a synthetic progestin and untreated postmenopausal women who were not estrogen-primed showed minimal epithelial proliferation. Endometri al glandular proliferation is inhibited by endogenous progesterone in premenopausal women. Endometrial proliferation is markedly reduced in premenopausal women receiving a synthetic progestin and in untreated p ostmenopausal women. CONTRACEPTION 1998;57:399-403 (C) 1998 Elsevier S cience Inc. All rights reserved.