Complement activation fragment Bb in early pregnancy and spontaneous preterm birth.

ABSTRACT

OBJECTIVE: The objective of this study was to determine whether an elevated level of the complement activation fragment Bb in early pregnancy was associated with spontaneous preterm birth (SPTB) at less than 34 weeks' gestation or SPTB between 34 and 37 weeks' gestation (late SPTB). STUDY DESIGN: This was a prospective study of 784 women enrolled at less than 20 weeks' gestation. RESULTS: Following exclusions, 13 women (1.7%) had a SPTB at less than 34 weeks' gestation and 25 (3.2%) a SPTB between 34 and 37 weeks' gestation. Women with Bb in the top quartile were 4.7 times more likely to have an SPTB less than 34 weeks' gestation as compared with women who had levels of Bb in the lower 3 quartiles (95% confidence interval [CI] 1.5-14, P = .003). There was no association between Bb and late SPTB (relative risk 0.8, 95% CI 0.3-2). CONCLUSION: A significant relationship was found between an elevated Bb in early pregnancy and SPTB less than 34 weeks' gestation. These results suggest that inflammatory events in early pregnancy are part of the pathogenic mechanisms of this condition.