library_construction_protocol: Fresh placental samples were macroscopically dissected from the central region of the maternal-facing surface to separate the decidual and trophoblast layers. The decidual layers were cut into small pieces and digested with 1 mg/mL collagenase type IV and 200 U/mL DNase I in Roswell Park Memorial Institute (RPMI)-1640 medium for 2–3 h at 37 °C. Thereafter, red blood cells (RBCs) were removed from the suspensions and filtered through a 70 μm cell filter. Decidual mononuclear cells were isolated using 40/80% Percoll density gradient centrifugation. Library was performed according to the manufactor's instruments (BD Rhapsody).