Abstract: Objective：To compare the expressions of progesterone receptor （PR） and progesterone induced blocking factor （PIBF） in the decidua tissues of early normal pregnancy and spontaneous abortion in early gestation stage. Methods：Twenty-five cases of early spontaneous abortion women （as the study group） and 20 cases of healthy women with early normal pregnancy （as the control group） were recruited. The expressions of PR and PIBF in the decidua tissues were detected by the streptavidin peroxidase immunostaining. Results：PR and PIBF expressed in the decidua tissues of both groups. There was no significant difference in the expression positive rates of PR and PIBF between two groups （χ2=0.002，P＝0.975； χ2=0.006，P＝0.950），but the expression intensity of PR and PIBF in the control group were stronger than those of the study group（Zc=2.261，P＝0.020；Zc=2.463，P＝0.010）. Conclusions：The lower expressions of PR and PIBF in the decidua tissue could be associated with early spontaneous abortiｏｎ，ｗhich reflected a pathway of the maternal complicated network related to early spontaneous abortion.

Key words: Abortion, spontaneous, Decidua, Receptors, progesterone, Progesterone-induced blocking factor