Serum progestagen-associated endometrial protein (PEP) levels in conception versus nonconception cycles following in vitro fertilization-embryo transfer

Abstract
The human endometrium synthesizes a specific protein known as the progestagen-dependent endometrium protein (PEP) which rises from early to late luteal phase. The PEP levels follow the pattern of the endometrial biopsy more than the serum progesterone (P) levels (4). Late luteal-phase serum PEP levels were evaluated as well as serum P in mid-luteal phase in patients undergoing IVFET. Comparisons were made between conceivers and nonconceivers and between aborters and nonaborters. Both serum PEP and late luteal P levels were significantly higher in pregnant patients but no differences in mid luteal P levels were seen. No difference was seen in aborters vs nonaborters. It is still inconclusive whether the higher late luteal PEP levels contribute to the greater likelihood of pregnancy or are a result of the pregnancy.