Transcriptomic patterns in early-secretory and mid-secretory endometrium in a natural menstrual cycle immediately before in vitro fertilization and embryo transfer.

OBJECTIVE: This study aimed to evaluate the endometrial transcriptomic patterns in the early secretory phase (ESP) and mid-secretory phase (MSP) of the natural menstrual cycle before in vitro fertilization and embryo transfer (IVF-ET).

METHODS: Thirty patients whose endometrial tissues were obtained from the ESP or MSP of a natural menstrual cycle immediately before IVF-ET were included. Endometrial dating was histologically confirmed as ESP (cycle days 16-18) or MSP (cycle days 19-21), according to the noyes criteria. The patients were divided into two groups depending on the IVF-ET outcome: pregnant (n=14; 7 in ESP and 7 in MSP) or non-pregnant (n=16; 8 in ESP and 8 in MSP). Differentially expressed genes (DEGs) in the MSP, compared to the ESP, were identified using NanoString nCounter (COMPANY, CITY, STATE, COUNTRY) data for both the pregnant and non-pregnant groups.

RESULTS: Thirteen DEGs in the pregnant group and 11 DEGs in the non-pregnant group were identified in the MSP compared to those in the ESP. In both groups, ADRA2A, IRAK2, ADAMTS15, SERPINE1, ITGB3, TMEM252, HAP1, CDCD4A, and ITGA2 were upregulated in the MSP, compared to the ESP. TMEM37, GLB1L2, RND3, and CYP24A1 were upregulated in the MSP only in the pregnant group. ADAMTS8 was downregulated and monoamine oxidase A (MAOA) was upregulated in the MSP only in the non-pregnant group.

CONCLUSION: Transcriptomic patterns in the endometrium immediately before IVF-ET appear to differ according to the IVF-ET outcome. These novel DEGs, which have not been previously studied, may have functional significance during the window of implantation and serve as potential biomarkers of endometrial receptivity.