Coagulation and Fibrinolysis in Normal Pregnancy and Complicated Pregnancy

Pregnancy induces significant physiological changes in the hemostatic system, leading to a hypercoagulable state to prevent postpartum hemorrhage. These adaptations involve alterations in coagulation and fibrinolysis, which can be further modified in complicated pregnancies such as gestational diabetes mellitus (GDM) and preeclampsia (PE).

This study investigated coagulation and fibrinolysis parameters in healthy pregnancies across different gestational stages and compared them to GDM and PE in the third trimester.

In this retrospective study, 293 pregnant women undergoing prenatal check-ups were enrolled. Coagulation parameters (prothrombin time, PT; activated partial thromboplastin time, APTT; thrombin time, TT; and fibrinogen, FIB) and fibrinolysis parameters (fibrin/fibrinogen degradation products, FDP; D-dimer; plasminogen activator inhibitor-1, PAI-1; tissue plasminogen activator, tPA; and plasmin-α2-plasmin inhibitor complex, PIC) were measured and compared across groups: non-pregnant controls, healthy pregnancies (first trimester, third trimester, delivery), GDM, and PE.

In normal pregnancy, all gestational stages showed significantly shortened PT, APTT, and TT and elevated FIB, FDP, D-dimer, PAI-1, and tPA compared to non-pregnant controls. FDP and D-dimer increased progressively with gestation. Compared to the third trimester, GDM was characterized by significantly higher PAI-1 and tPA but lower PIC, whereas PE was characterized by significantly higher PAI-1 and PIC, prolonged APTT, and lower tPA. Furthermore, among healthy women at delivery and those with GDM, overweight and obesity were associated with significantly increased PAI-1 levels.

As pregnancy progresses, enhanced coagulation with hypofibrinolysis occurs in normal pregnancy, and further hypofibrinolysis is the primary thrombotic driver in GDM and obesity. PE presents a more complex alteration in both coagulation and fibrinolytic pathways.