LEVONORGESTREL-RELEASING INTRAUTERINE DEVICE-WEARING WOMEN EXPRESS CONTRACEPTIVE GLYCODELIN-A IN ENDOMETRIUM DURING MIDCYCLE - ANOTHER CONTRACEPTIVE MECHANISM

Intrauterine devices (IUDs) exert contraceptive action by interfering with sperm transport, ovum development, fertilization and implantation , Glycodelin A (GdA) is a uterine glycoprotein that has local contrace ptive activity by inhibiting sperm-egg binding, GdA is normally absent from endometrium during the fertile midcycle and it is not expressed until the fifth postovulatory day. The phase of menstrual cycle addres sed in this study covers the phase when conception is most likely to f ollow an unprotected intercourse and when GdA is normally absent, We p resent here evidence that levonorgestrel-releasing IUD (LNg-IUD) is ac companied by 'inappropriate' expression of GdA in endometrium between days 7 and 16 of the menstrual cycle (six out of six cases), The same was also found in copper-releasing IUD (Cu-IUD)-wearing women, but les s frequently (four out of 11 cases, P < 0.0345, Fisher's exact test), Zn-situ hybridization localized GdA mRNA into endometrial glands in th e midcycle endometrium, confirming the cellular site of synthesis. Bas ed on the potent inhibitory activity of GdA on sperm-egg binding, the presence of GdA in uterine glands of IUD, wearers may lead to prior ex posure of sperm to contraceptive GdA, thus contributing to the contrac eptive activity of the IUD.