Abstract: Objective：To detect the expression of miR-203 in endometrium and decidua， and explore its significance during decidualization of endometrium. Methods：14 secretory endometria， 16 early pregnancy deciduas and 18 spontaneous miscarriage deciduas were collected in the study. MiR-203 expression level was detected by quantitative polymerase chain reaction（qPCR）. And IGF2R was predicted as the target gene of miR-203 respectively. Furthermore，the miRNA expression of IGF2R was detected by fluorescence quantitative PCR. Results：The expression of miR-203 in secretory endometrium was higher than that in spontaneous miscarriage decidua and early pregnancy decidua （P＜0.05）. Moreover，IGF2R was increased in early pregnancy，comparing with secretory endometrium and spontaneous miscarriage decidua（P＜0.05）. Conclusions：The expression of miR-203 may be associated with decidualization by targeting IGF2R. And IGF2R might associate with early pregnancy maintenance.

Key words: Endometrium, Decidua, MicroRNAs, Receptor, IGF type 2