Fibrinogen levels in pregnancy have a prognostic role in preeclampsia and in massive obstetric haemorrhage

      Aim: The authors aimed at estimating reference values of fibrinogen levels in pregnancy based on large outpatient obstetric population and analysing the results in relation to outcome.
      Methods: Routine haemostaseology studies with additional estimation of fibrinogen levels were sought for asymptomatic obstetric outpatients. Fibrinogen levels were measured according to the Clauss method using BCS2 and BCSXP2 automatons. The prognostic role of low fibrinogen levels was studied retrospectively in a 5-year series of cases of obstetric haemorrhage.
      Results: The mean fibrinogen level (95%CI) of the entire study population was 4.94 g/L (3.51–7.38 g/L). Distribution of the actual values showed an apparent dichotomy regardless of the gestational age and the time between sampling and delivery. There were hardly any cases with a value of 5 g/L fibrinogen level. Both the population with < 5 g/L fibrinogen-level and total population had a 5 percentile limit (3.43 g/L and 3.51 g/L, respectively) which was higher than the upper limit of normal in non-pregnant population. Comparison of basic obstetric parameters of subpopulations with ≥5 g/L and <5 g/L fibrinogen levels showed that the former group had higher gravidity and parity, and had an increased odds of developing preeclampsia. There was no difference between the two groups with regards to age, gestational age at delivery, preterm delivery rate, Caesarean section frequency, mean birthweight and the frequency of gestational diabetes. In the five-year retrospective study of obstetric haemorrhage the authors identified 12 cases of massive transfusion (RBC + FFP). Three out of the 12 cases ultimately required hysterectomy. All three cases had <3 g/L fibrinogen levels before the start of labour. Further two cases of major obstetric haemorrhage had <3 g/L fibrinogen levels before the start of labour.
      Conclusions: Fibrinogen levels are significantly higher during pregnancy than in the non-pregnant population. Since quantitative assessment of fibrinogen level was based on the Clauss method, it is not certain whether higher fibrinogen levels are associated with higher fibrinogen antigen levels or not. The high frequency of ≥5 g/L fibrinogen levels in our pregnant population suggests that it is an acquired condition, but this conclusion needs further investigations. It is also stipulated that extremely high fibrinogen levels might be caused by abnormally constructed fibrinogen molecules.