Antenatal fibrinogen concentrations and postpartum haemorrhage

It is unclear whether antenatal fibrinogen concentrations are associated with postpartum haemorrhage.

This retrospective study included 871 women with a singleton pregnancy but no known risk factors for postpartum haemorrhage, in whom fibrinogen concentration was measured within the 21 days before delivery. Correlation between antenatal fibrinogen concentrations and estimated blood loss was analysed. We tested the hypothesis that the risk of postpartum haemorrhage was higher in women with antenatal fibrinogen concentrations of <3.3 g/L. Postpartum haemorrhage was defined as an estimated blood loss ⩾700 mL following vaginal delivery and ⩾1000 mL following caesarean delivery.

In women delivering vaginally (n=337), estimated blood loss tended to increase with decreasing antenatal fibrinogen concentration (R=-0.107, P=0.05), median fibrinogen concentration was significantly lower in 69 women with postpartum haemorrhage than in 268 women without postpartum haemorrhage (3.93 vs. 4.18 g/L, P=0.025), and postpartum haemorrhage occurred significantly more often in women with fibrinogen concentrations <3.3 g/L than in those with concentrations ⩾3.3 g/L (38% [11/29] vs. 19% [58/308], P=0.018). In women undergoing caesarean delivery (n=534), median fibrinogen concentration did not differ between those who experienced postpartum haemorrhage (n=128) and those who did not (n=406) (4.18 g/L vs. 4.07 g/L, P=0.43). Antenatal fibrinogen concentrations of <3.3g/L were not associated with higher rates of postpartum haemorrhage (26% [11/43] vs. 24% [117/491], P=0.80).

Antenatal fibrinogen concentration <3.3g/L may be a risk factor for postpartum haemorrhage among women following vaginal delivery.