Objective: Progesterone receptor membrane component 1(PGRMC1) is one of membrane progesterone receptors that to directly activates intracellular signaling cascades. Although PGRMC1 may have anti-inflammatory and anti-apoptotic actions, the role of PGMC1 in fetal membranes remains unclear. Preterm labor (PTL) and preterm premature rupture of membrane (PPROM) are association with inflammation in fetal membranes. The purpose of our study was to determine the expression of PGRMC1 in fetal membranes with PTL, PPROM, and acute histologic chorioamnionitis (HCA). Methods: Full thickness of fetal membranes were obtained from women with preterm birth (PTB), gestational age matched (32-34weeks of gestational age), combined PTL without HCA (PTL, n=10), PPROM without HCA (PPROM, n=10), and PTB with HCA (HCA, n=10) and from women undergoing term elective cesarean delivery without labor or HCA (T, n=9). The expression of PGRMC1 was assessed by Western blot and densitometric analysis. Because CD14 is a component of the innate immunity, CD14 was used for inflammatory indicator. Immunohistochemistry (IHC) with specific antibodies to PGRMC1 and CD14 was done. Nonparametric statistics was used for analysis. Results: All layers of fetal membrane, amnion, chorion, and deciduas had PGRMC1 expression. PGRMC1 expressions in PTB including PTL (mean 0.28±0.07, p=0.01), PPROM (mean 0.59±0.19, p=0.22), and HCA (mean 0.16±0.07, p=0.003) were decreased than in those of T (mean 0.87±0.48). Especially, in PTB with HCA PGRMC1 expression was significantly decreased compare to PTL and PPROM (p=0.006, p=0.001, respectively). CD 14 was inversely expressed proportional to PGMC1 (r = - 0.518, p =0.002). PGRMC1 expression in PPROM was higher than those of PTL (p=0.002), although there was no difference in expression level of CD 14 (p=0.458). IHC showed that PGRMC1 was predominantly in the cytoplasm of cells, and represented immunoreactivity consistent with immunoblotting results. Conclusion: PTB with PTL, PPROM, and especially HCA are associated with a decreased PGRMC1 in fetal membranes along with inversely increased of CD 14. PGRMC1 expression in PPROM was higher than those of PTL. Acknowledgements: This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea goverment (No. 2017R1D1A1B03029882)