Pregnancy-associated plasma protein A in the human endometrium is dependent on the effect of progesterone

The biotin-avidin immunoperoxidase method was used to study pregnancy-associated plasma protein A (PAPP-A) in the endometrium of 102 pre- or postmenopausal women. Endometria in the proliferative phase (n = 27) or early secretory phase (days 1-3 postovulation; n = 12), cystic glandular hyperplasia (n = 12), and postmenopausal endometria of untreated (n = 7) or estrogen-treated (n = 5) women were all PAPP-A negative. By contrast, PAPP-A was invariably present in the endometrium during the normal secretory phase after day 3 of ovulation (n = 28), during cyclic progestogen treatment of pre-menopausal women (n = 6), and during estrogen-progestogen replacement therapy of postmenopausal women (n = 5). These results suggest that the occurrence of PAPP-A in the endometrium is progesterone dependent.