Aim: To investigate the effects of levels of tissue factor (TF) and tissue factor pathway inhibitor (TFPI) proteins in blood of placental abruption (PA) puerperants and newborns and cord blood on their blood clotting function. Methods: From October 2006 to April 2007, 11 PA puerperant blood samples, 11 fetal cord blood samples and 11 newborn blood samples were enrolled at First Affiliated Hospital of Sun Yet-sen University, and 4 cases were term birth, others with fetal age of 29-36 weeks, including 5 male infant blood samples and 6 female infant blood samples. The 15 control samples at the same time were collected from puerperants and newborns of Guangzhou Women and Children's Hospital. The samples were gotten 24 hours before labor from mothers, at the time of delivery from cord blood and 2 hours after birth. These puerperants were neither having the history of hematological system diseases nor using drugs that might affect the coagulation function. The plasma levels of TF and TFPI antigen were measured by enzyme linked immunosorbent assay (ELISA). Pathological data and normal samples were collected with the agreement of puerperants and their family members. Results: 1 The plasma level of TF antigen in PA puerperants, newborns and cord blood were significantly higher than the normal controls (P<0.05). 2 The levels of TFPI in PA puerperants, newborns and cord blood were significantly decreased (P<0.01). 3 The same results of the ratio TFPI/TF were obviously lower than the normal controls in the PA puerperants (P<0.01). Conclusion: The procoagulant activitities are enhanced in PA puerperants, newborns and cord bloods, and the anti-procoagulant activities are decreased. These are associated with hypercoagulable state.