PDCD1 and abortion: Similarly, our previous studies found that adoptive transfer of Blimp‐1+ or IL‐27‐treated Treg cells to an LPS‐induced abortion‐prone mouse model effectively reduced the embryo resorption rate and improved placental vascular development by promoting the accumulation of Treg cells in the decidua and the expression of negative signaling molecules such, as Tim‐3 and PD‐1, in Treg cells.[38] Hence, the positive effects of the adoptive transfer of Treg cells on reducing embryo absorption in mice provide insights for improving adverse pregnancy outcomes in older pregnant mice.