The role of thrombin in preterm parturition

OBJECTIVE: Previous reports from our laboratory have shown that thrombin is a potent uterotonic agonist; those studies have suggested a role for throm bin during parturition, especially with regard to intrauterine bleeding. Th rombin activation can be quantified in peripheral blood by measurement of t hrombin-antithrombin Ill (TAT) complex levels. This study sought to determi ne whether thrombin activation, as measured by thrombin-antithrombin Ill le vels, is associated with premature labor. STUDY DESIGN: Thrombin-antithrombin Ill levels were measured in patients an d control subjects with preterm labor. Quantitative TAT levels were determi ned by use of an enzyme-linked Immunoassay with a working range from 0 to 6 0 ng/mL. All patients were monitored for pregnancy outcome. Receiver operat ing curve analysis was performed to determine the optimal TAT cutoff values . Further statistical analyses with one-way ANOVA, the chi (2) test, or the Fisher exact test were performed to determine statistical significance (P < .05). RESULTS, Patients admitted with preterm labor who were subsequently deliver ed within 3 weeks had significantly higher mean TAT levels (7.80 +/- 2.86 n g/mL; P < .05) than control subjects (5.77 +/- 1.43 mL) or patients with pr eterm labor who were not delivered within 3 weeks of presentation with pret erm labor (5.57 +/- 1.69 ng/mL; P < .05). Given a diagnosis of preterm labo r, a TAT level of 8.0 ng/mL had a positive predictive value of 80% for deli very within 3 weeks of enrollment. CONCLUSIONS: This study showed that TAT levels are elevated in patients wit h preterm labor who are destined to deliver before term. These results sugg est that preterm, labor resulting in premature delivery is associated with the activation of thrombin. Future studies will further elucidate the role of thrombin In preterm parturition and confirm whether tests for thrombin a ctivation can accurately identify those patients destined for preterm, deli very.