Rnasafer reagent

Cervix specimens were collected by using a sterile single-tipped CultureSwab. The swab was inserted into the cervix before hysteroscopy, rotated 360°, held for 10 s, removed and placed into the sterile collection tube, then stored at −80°C, avoiding vaginal walls contact. Uterine endometrium was taken from lower segment during hysteroscopy and immersed in 1 mL of RNAsafer reagent (R4811-02, Magen, China). Endometrial specimens were stored at 4°C overnight before transfer to −80°C.

Cervix specimens were collected by using a sterile single-tipped CultureSwab. The swab was inserted into the cervix before hysteroscopy, rotated 360°, held for 10 s, removed and placed into the sterile collection tube, then stored at −80°C, avoiding vaginal walls contact. Uterine endometrium was taken from lower segment during hysteroscopy and immersed in 1 mL of RNAsafer reagent (R4811-02, Magen, China). Endometrial specimens were stored at 4°C overnight before transfer to −80°C.

Blood samples were collected into anticoagulant tubes, mixed with exactly three volumes of RNASafer Reagent (Magen) and stored under strict standard operating procedure conditions temporarily at −80°C before batch analysis. Hipure PX Blood RNA Kits (Magen) were used to extract total RNA. Concentrations of isolated RNA were detected using a Qubit 3.0 fluorometer (Invitrogen, Carlsbad, California). Isolated RNA integrity was detected with an Agilent 2100 bioanalyzer (Applied Biosystems, Carlsbad, CA). KAPA RNA HyperPrep Kits with RiboErase for Illumina (Kapa Biosystems, Woburn, MA) were used to prepare a high-throughput sequencing library with 2 μg of total RNA. Illumina Hiseq X ten was used to perform paired-end (PE150) sequencing.