RESUMEN
BACKGROUND: Severe postpartum hemorrhages (PPH) represent a significant cause of maternal morbidity/mortality, but little is known about its hemostasis-related risk factors. Among the 32 463 women enrolled in the NOHA First cohort, 317 developed severe PPH (S-PPH group), 1269 non-severe PPH (NS-PPH group) and the remaining individuals were considered as control women (C group). METHODS: We performed a case-control study, including 317 triplets of women allocated from the three groups that shared the same clinical characteristics as the S-PPH group. RESULTS: From values obtained 6-9 months after delivery, low (but not-deficient) levels of fibrinogen, von Willebrand factor (VWF) antigen, factor (F) XI, platelet CD42b, TRAP-induced increase of platelet CD41a and high values of serum residual prothrombin activity or closure aperture times using the collagen-ADP cartridge on the PFA-100 system, and blood group O, were independently associated with a significant risk of severe PPH. Being positive for at least two of these eight variables was found in 1.6%, 3.5% and 20.8% of the women from the C, the NS-PPH and the S-PPH groups, respectively, the odds ratio for S-PPH in such a case being 16.4, 95%CI (6.5-41), P < 0.0001. CONCLUSIONS: Women with some hemostasis-related variables at the low or high end of the population distributions are prone to the severe forms of PPH. Clinical trials will allow us to know if acting on these risk factors can lower the clinical severity of PPH.