Objective To investigate the pathogenesis of unexplained recurrent spontaneous abortion(URSA). Methods We observed the embryo loss rate (ELR)in the CBA/J ×DBA/2 murine spontaneous abortion model in 5 separate batches(experimental group) as compared with CBA/J ×BALB/c (non-abortion prone, control group)and determined the concentration of type Th1、Th2 cytokine from female CBA/J. Results In 5 separate batches, the ELR of CBA/J ×DBA/2 (27.27%~32.20%)was increased significantly as compared with the cont...