Changes in Fibrinogen and D-Dimer During Complicated and Uncomplicated Pregnancy

The increase in fibrinogen levels is vital for the formation of a prothrombotic state during gestation to counter-bleeding challenges at delivery. However, pregnancy complications characterized by systemic inflammatory response syndrome may consume fibrinogen, resulting in elevated D-dimer levels.

Our study is based on a total of 16 768 pregnant women who delivered between December 1, 2013, and December 1, 2018, to study fibrinogen and D-dimer changes during gestation under normal and multiples of pathogenic states.

Compared with nonpregnant women (3.04[3.02-3.08]), pregnant women depicted higher fibrinogen levels throughout gestation (p < 0.001). In the uncomplicated group, fibrinogen levels increased throughout the first (3.28[3.26-3.29]), second (4.04[4.01-4.07]), and third trimesters (4.40[4.38-4.41]) but dropped at delivery (4.30[4.28-4.31]), similar to the changing pattern of the pregnancy-related complication group and pre-existing disorder group. Women with pregnancy-related complications showed significantly higher mean fibrinogen levels throughout gestation (p < 0.001), except for placental abruption, where, it decreased from the third trimester and was lower than that of uncomplicated pregnancies (3.89[3.60-4.17] vs. 4.40 [4.38-4.41], p = 0.001). Among uncomplicated pregnancies, D-dimer grew rapidly throughout the first trimester (0.09[0.06-0.15]), second trimester (0.28[0.19-0.40]), third trimester (0.51[0.36-0.78]), and delivery (0.70[0.47-1.03]).

Women with pregnancy-related complications and pre-existing disorders shared similar changing patterns; however, the D-dimer of women with placenta accreta presented higher levels than those with uncomplicated pregnancies since the first trimester. We concluded that fibrinogen levels are expected to increase steadily, but in patients with placental abruption, fibrinogen levels dropped during the third trimester. D-dimer levels typically rise consistently throughout pregnancy, yet in patients with placenta accreta, they show abnormal elevation since an early stage of pregnancy.