EMERGENCY CONTRACEPTION ALTERS PROGESTERONE-ASSOCIATED ENDOMETRIAL PROTEIN IN SERUM AND UTERINE LUMINAL FLUID

Objective: To evaluate the effect of high-dose oral contraceptives on serum and uterine luminal fluid progesterone-associated endometrial pr otein in the luteal phase. Methods: Five ovulatory women participated in the study. In a control cycle, serum and uterine lavage samples wer e collected on luteal day 11. In the next cycle, on luteal day 9, the participants were given two 50-mu g ethinyl estradiol-norgestrel table ts, repeated 12 hours later. Serum and uterine lavage samples were col lected 48 hours (luteal day 11) after the last dose and analyzed by tw o-dimensional polyacrylamide gel electrophoresis and radioimmunoassays of the serum. Results: Progesterone-associated endometrial protein le vels were lower in sera from treated compared with control cycles. Ana lysis of serum levels of this protein by two-dimensional polyacrylamid e gel electrophoresis did not reveal bands corresponding to the known size and charge characteristics (27 kd and pI of 4.9) in either contro l or treatment samples. On the other hand, in uterine lavage samples, a complete suppression of the 27-kd, pI-4.9 species was evident after treatment. Conclusion: High-dose ethinyl estradiol-norgestrel emergenc y contraception effectively suppresses progestetone-associated endomet rial protein in the midluteal uterus, potentially altering the endomet rial environment unfavorably and affecting the survival of the early e mbryo.