Objective To investigate the treatment of threatened abortion progesterone maternal serum pro-gesterone -induced blocking factor (PIBF)levels and clinical significance,in order to be able to provide theoretical references of progesterone treatment of threatened abortion.Methods Threatened abortion women (study group)and non -threatened abortion women (control group),50 patients in the observation group given progesterone therapy, enzyme -linked immunosorbent assay (ELISA)was used to detect serum progesterone and PIBF levels of the obser-vation group before treatment and two weeks later,the control group was selected and named after two weeks.Results Observation group after treatment 47 patients progesterone tocolysis successful,success rate was 94.00%,tocolysis bleeding stop time 8.42d,abdominal pain time 11.32d.PIBF of the observation group was (313.52 ±90.43)mmol/L, which was lower than that of the control group (398.47 ±104.25)mmol/L,the difference was statistically significant (t =10.90,P <0.05).The progesterone of the observation group after 2 weeks of treatment was (92.35 ±20.85)mmol/L, which was higher than that before treatment (74.49 ±14.22)mmol/L,compared with progesterone levels of the con-trol group at the same time (83.26 ±20.14)mmol/L and (78.05 ±15.38)mmol/L,the difference was statistically significant (t =7.96,8.11,P <0.05),PIBF after 2 weeks of treatment in the observation group was (510.73 ± 87.49)mmol/L,which was higher than that of the control group at the same time (498.26 ±69.88)mmol/L,the difference was statistically significant (t =4.35,P <0.05).Follow -up observation group miscarriage successful term delivery rate 95.74% of pregnant women,childbirth fetal malformations seen in the control group of pregnant women at term birth rate was 94.00%,no delivery fetal malformation,the difference of full -term delivery rate was not statis-tically significant (P >0.05).Conclusion Reduced PIBF during early pregnancy may be one of the reasons of threatened abortion,the use of progesterone therapy can increase PIBF expression,possibly through this pathway plays a role in tocolysis,so when using progesterone tocolysis monitoring PIBF levels helps evaluate the efficacy of tocolysis.