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Hemostasis during normal pregnancy and puerperium
1Department of Obstetrics and Gynecology, Göteborg University and Sahlgrenska University Hospital, Sweden. margareta.hellgren@vgregien.se
Seminars in Thrombosis and Hemostasis
|April 24, 2003
Summary
Pregnancy shifts the hemostatic balance towards hypercoagulability, reducing bleeding risks during delivery. These hemostatic changes normalize postpartum, but testing is recommended 3 months after delivery.
Area of Science:
- Obstetrics and Gynecology
- Hematology
- Physiology
Background:
- Normal pregnancy is characterized by a shift towards a hypercoagulable state.
- This hemostatic balance change aims to mitigate bleeding complications during childbirth.
- Key physiological alterations include increased coagulation factors and diminished fibrinolytic capacity.
Purpose of the Study:
- To detail the hemostatic system's adaptations during normal pregnancy.
- To describe the hemostatic changes during labor and delivery.
- To outline the postpartum normalization of hemostasis and recommend optimal timing for testing.
Main Methods:
- Review of global hemostasis tests (Sonoclot, Thromboelastogram).
- Analysis of specific coagulation markers: prothrombin complex level (PT/INR), activated partial thromboplastin time (aPTT), platelet count, and coagulation factors.
- Assessment of fibrinolytic markers, including plasminogen activator inhibitor-1 (PAI-1) and plasminogen activator inhibitor-2 (PAI-2).
Main Results:
- Pregnancy demonstrates hypercoagulability with increased thrombin generation and acquired activated protein C resistance.
- Platelet counts may decrease in the third trimester (gestational thrombocytopenia), but platelet turnover is typically normal.
- Coagulation factors and fibrinogen increase, while Factor XI decreases; fibrinolytic capacity is reduced due to elevated PAI-1 and PAI-2 levels.
Conclusions:
- Pregnancy induces significant hemostatic changes, including hypercoagulability and reduced fibrinolysis, which are essential for managing delivery.
- Labor involves consumption of platelets and factors, followed by enhanced fibrinolysis postpartum.
- Hemostasis returns to baseline within 4-6 weeks postpartum, with some markers normalizing later; testing should be deferred until 3 months postpartum.