Evidence from three cohort studies on the expression of MUC16 around the time of implantation suggests it is an inhibitor of implantation

PURPOSE: To examine the expression of MUC16 in the endometrium peri-implantation period in three different cohort studies. METHODS: This was a retrospective observational cohort study. A total of 245 participants were recruited in three separate cohort studies: (1) women with recurrent miscarriage (n = 50) and fertile controls (n = 29); (2) women who had high (n = 20) or normal (n = 20) progesterone on the day of hCG trigger in ovarian stimulation cycle for IVF; and (3) women who did (n = 95) or did not (n = 31) conceive following frozen embryo transfer in HRT cycles. All subjects had archived endometrial samples precisely taken on LH+7 in natural cycles, or hCG+6 in ovarian stimulation cycles, or P+5 in HRT cycles. The H-score (median, range) of MUC16 in the luminal epithelium and glandular epithelium was determined by using immunohistochemistry. RESULTS: The median (range) of H-score of MUC16 in the luminal epithelium (1) in women with recurrent pregnancy loss was 23.7 (0-300), which was significantly (P < 0.05) lower than that of 118.4 (7.7-300) in fertile controls; (2) in women with elevated progesterone on the day of hCG administration (147.8, 18.0-230.1), significantly (P < 0.05) higher than that of women with normal progesterone (61.0, 2.3-205.3); (3) in women who conceived (23.1, 0-250.3), significantly (P < 0.001) lower than that in women who did not conceive (58.4, 0-300). CONCLUSION: The expression of MUC16 in all three cohort studies is consistent with it being an inhibitor of implantation.