Venous thromboembolism and anticoagulant therapy in pregnancy.
BACKGROUND
Venous thromboembolism (VTE) is a leading cause of maternal mortality in western countries. Many of these deaths could be prevented by optimal prophylaxis and management.


OBJECTIVE
The aim of this study was to examine the current literature to assess the risk of VTE in pregnant women and to identify the most effective and safe anticoagulant therapy.


METHODS
A search was conducted using the major electronic databases of PubMed and MEDLINE 1996-October 2005 using the following key words: Pregnancy, venous thrombosis, thrombophilia, prosthetic heart valves, anticoagulants, heparin, low-molecular-weight heparin, coumarin, and warfarin.


RESULTS
The common risk factors for VTE during pregnancy are age >35 years, obesity, operative delivery, thrombophilia, and a family or personal history of VTE. Coumarins are unsuitable for use during pregnancy because of embryopathy and risk of fetal bleeding. Low-molecular-weight heparins (LMWHs), such as enoxaparin and dalteparin, are safer and more convenient than unfractionated heparin (UFH). LMWH is now the agent of choice for pharmacologic thromboprophylaxis and treatment of VTE during pregnancy. Women with a suspected VTE should receive anticoagulant therapy until an objective diagnostic test is performed, unless there is a clear contraindication to anticoagulation. If a VTE is confirmed, anticoagulant treatment should be continued throughout pregnancy. These patients usually, require at least 6 months of anticoagulation, and treatment should be continued until at least 6 weeks postpartum. Management of women with prosthetic heart valves in pregnancy is controversial; while coumarin treatment is more effective than UFH for thromboprophylaxis in the mother, UFH is associated with a better outcome for the fetus. Coumarin embryopathy can be avoided if heparin is substituted by 6 weeks' gestation. The limited data on LMWH in women with prosthetic heart valves suggest that it compares favorably with UFH.


CONCLUSIONS
LMWH is now the anticoagulant of choice for the treatment and prevention of VTE in pregnancy. However, the management of women with prosthetic heart valves requiring anticoagulation in pregnancy remains controversial as coumarins appear safer for the mother, but heparin is associated with less fetal morbidity and data on LMWH are limited.
University of Glasgow, Division of Developmental Medicine, Maternal and Reproductive Medicine, Glasgow Royal Infirmary, Scotland, UK. I.A.Greer@clinmed.gla.ac.uk
Ian A
IA
Greer
D000328:Adult; D000925:Anticoagulants / Q000627:therapeutic use*; D005260:Female; D005343:Fibrinolytic Agents / Q000627:therapeutic use; D006495:Heparin, Low-Molecular-Weight / Q000627:therapeutic use; D006801:Humans; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000188:drug therapy* / Q000517:prevention & control; D011295:Prenatal Care / Q000379:methods; D011655:Pulmonary Embolism / Q000188:drug therapy* / Q000517:prevention & control; D012307:Risk Factors; D020246:Venous Thrombosis / Q000188:drug therapy* / Q000517:prevention & control; D016387:Women's Health
D000925:Anticoagulants; D005343:Fibrinolytic Agents; D006495:Heparin, Low-Molecular-Weight