High fibrinogen content in pregnant women – pathology or overdiagnosis?
Authors: Leush S.S. 
Published: September 2024

An increased fibrinogen (FG) concentration during pregnancy is considered a protective mechanism against bleeding during childbirth. An enlarged amount of FG increases the aggregation of erythrocytes, blood plasma viscosity, microvascular resistance – permanent elements of the pathogenesis of arterial hypertension, stroke, coronary heart disease. It is also associated with an increased likelihood of development of preeclampsia and stroke with subsequent neurological disorders.In addition to its undeniable importance for hemostasis, FG is directly related to several physiological and pathophysiological conditions, such as infection, wound healing, tumorigenesis, and the severity of atherosclerosis. It also has a decisive role in the development of pregnancy. Maternal FG is necessary for the progress of pregnancy, as it stabilizes the utero-placental connection at the fibrinoid layer of the fetal-maternal junction. No reports on the study of pathological forms of FG in Ukraine were found.The objective: to compare the indicators of FG concentration and related elements of the blood coagulation system of pregnant and parturient women in different gestational periods and after childbirth.Materials and methods. Blood components from the ulnar vein of 30 women in labor at a gestation period of 22–27 weeks (extremely preterm birth (EPB) – I group), 37 women in labor at a term of 28–34 weeks (early preterm birth (PB) – II group) and 40 women with gestational period 37–41 weeks (control group (CG) – III group) was studied. In the collected samples the content of FG, D-dimer (Dd), prothrombin index (PI), activated partial thromboplastin time (APTT), as well as the levels of hemoglobin (Hb), hematocrit (Ht) and total protein (TP) of the blood plasma were determined.All women in labor were hospitalized in the active phase of the I labor period and did not receive infusion therapy. In terms of gestation, corresponding to EPB, early PB and CG, 10 pregnant women who were on outpatient registration at the Perinatal Center were examined for comparison of the studied indicators outside of labor.Indicators of the biochemical coagulogram were studied on a Helena C-2 semi-automatic coagulometer (Helena Biosciences, Great Britain).Results. The FG concentration increased from 4.2±0.56 g/l in the term 22–27 weeks to 4.4±0.57 g/l before delivery with a diapason of 3.5 to 5.0 g/l. In all parturients, the FG concentration was lower than 4.5 g/l, respectively by group: 4.5±0.81; 4.1±0.74 and 4.1±0.65 g/l (р<0.05). In 24 hours after delivery the FG concentration increased in CG to 5.0±0.82 g/l, and after 48 hours – to 5.3±1.19 g/l, which exceeded the indicators of parturients of the EPB and early PB groups and pregnant women of these same terms, in which the highest indicator was 4.5±0.81 g/l in the EPB group (p<0.05).An increase in the Dd index with growing gestational age was observed in all pregnant women (from 274±133.3 to 501±174.7 μg/l). It continued during the first postpartum day – up to 685±157.5 μg/l, decreased on the second day – 429±198.9 μg/l (p<0.05), approaching the indicators of the EPB and early PB groups (487±267.0 and 397±202.3 μg/l; p>0.05) and pregnant women of the same term.Hb decreased to 106±8.9 g/l, and Ht – to 35±6.1% with the progression of pregnancy. In parturients of the PB group, they were probably higher than the indicators of pregnant women of the corresponding terms, increasing on the second day after delivery – 110±6.7 g/l and 41±3.1%.There was no significant blood loss in the clinical groups. In all pregnant and parturient women the APTT and PI indicators varied from 27.0±3.51 s to 35.4±3.43 s and from 88±4.8% to 101±5.2%, respectively.Conclusions. 1. A gradual increase in the fibrinogen (FG) concentration with increasing gestational age from 4.2±0.56 g/l in 22–27 weeks to 4.4±0.57 g/l by the time of delivery indicates an increase in the level of FG in healthy pregnant women as an adaptive response of the body to the formation of an additional vascular system.2. An excessive FG increase is a consequence of hemoconcentration, not absolute hyperfibrinogenemia, and may be a sign of pathological processes underlying hypovolemia. In case of extremely preterm birth (EPB), the concentration of FG in the parturient was 4.5±0.81 g/l. Higher values of FG, hemoglobin, and hematocrit in parturients with EPB than in pregnant women at the same term are evidence of insufficient hemodilution, which can be considered as one of the pathogenetic mechanisms of premature labor.3. Laboratory indicators of the blood coagulation system – APTT, PI – in the absence of bleeding have no diagnostic value.