Abstract: Objective：To investigate the effect of aspinrin combined with prednisone on pregnancy outcome in patients with positive anti-phospholipid antibody（APA） undergoing in vitro fertility-embryo transfer（IVF-ET）. Methods: Fifty-two patients underwent IVF-ET who had positive anticardiolipin（ACA） or/and anti-beta 2 glycoprotein 1 antibody（Aβ2GP1） were randomly divided into two groups，one group treated with aspirin and prednisone at low doses， another untreated as control. Oocyte retrieval number，fertilization rate，cleavage rate，useful embryo rate，high quality embryo rate，implantation rate，clinical pregnancy rate，abortion rate were analyzed. Results: Between two groups，there were not significant differences in the oocyte retrieval rate and abortion rate（8.52±4.34 vs. 9.67±4.02，P=0.312；9.09% vs. 50%，P=0.05）. The treated group had higher fertilization rate （80.43% vs. 72.41%，P=0.032），cleavage rate（98.67% vs. 94.64%，P=0.045）， useful embryo rate （89.24% vs. 76.73%，P=0.001），high quality embryo rate （72.65% vs. 42.77%， P＜0.001）， and clinical pregnancy rate （66.67% vs. 33.33%，P=0.013） than control. Conclusions: Those patients with positive ACA and Aβ2GP1 but without recurrent abortion undergoing IVF-ET can be treated with aspirin and prednisone in low dose，which could be helpful to improve fertility rate， embryo quality，clinical pregnance rate，and IVF-ET outcomes.

Key words: Antibodies, anticardiolipin, Glycoproteins, Beta 2-glycoprotein I, Fertilization in vitro, Embryo transfer, Prednisone, Aspirin