The impact of prepartum factor XIII activity on postpartum blood loss

BACKGROUND Postpartum hemorrhage (PPH), a major cause of maternal mortality, has several known risk factors but frequently occurs unexpectedly. PPH incidence and related maternal morbidity and mortality are rising worldwide. OBJECTIVE To evaluate the impact of defined prepartum blood coagulation parameters on postpartum blood loss. METHODS This single-center, prospective cohort study analyzed prepartum activities of coagulation factors II and XIII and fibrinogen levels in 1300 women. Blood samples were obtained at labor onset and analyzed only after the last patient had delivered, to prevent a potential treatment bias. Blood loss was quantified using a validated technique. The influence of coagulation factors on measured blood loss was assessed by continuous outcome logistic regression. RESULTS Prepartum factor XIII activity strongly influenced measured blood loss: every one unit (%) increase in prepartum factor XIII was associated with an odds ratio of 1.011 (95% confidence interval, 1.006-1.015; P < .001) to keep blood loss below any given cut-off level. For illustration, this suggests that a 30% increase in factor XIII activity increases the odds of not suffering PPH (defined as blood loss ≥500 mL) by 38.9%. This effect remained significant after stratification for the delivery mode, when correcting for other risk factors, and was independent of the statistical model used. Factor II but not fibrinogen had a partially comparable, but much less pronounced, effect. CONCLUSION In the largest population analyzed for the influence of prepartum coagulation factors on PPH to date, prepartum factor XIII activity had a strong impact on postpartum blood loss across every statistical model and clinical subgroup. Our hypothesis that early replenishment of factor XIII levels might constitute a new tool in the prevention and effective early treatment of PPH should be evaluated in future trials