Expert review: prevention of obstetrical venous thromboembolism

Am J Obstet Gynecol. 2021 Sep;225(3):228-236. doi: 10.1016/j.ajog.2021.05.004. Epub 2021 May 8.


Venous thromboembolism represents a persistent proportionate cause of maternal mortality in the United States accounting for 9% to 10% of maternal deaths. Given that overall maternal mortality rose >40% since the late 1990s, it is likely that absolute venous thromboembolism mortality risk increased as well. This persistent risk may be secondary to increases in broad population-based risk factors for venous thromboembolism such as obesity and cesarean delivery. Widespread adoption of perioperative cesarean mechanical thromboprophylaxis is associated with reduced risk for venous thromboembolism events but has not been sufficient to reduce mortality. Experts agree that improved clinical care is required to reduce risk as it is unlikely that trends in venous thromboembolism risk factors will reverse course anytime soon. Experts further agree that improving prophylaxis and prevention may provide the largest benefit. However, how to best improve prophylaxis is highly controversial with both experts and guidelines in disagreement. In the United Kingdom, mortality risk decreased substantially following the 2004 recommendations for broader heparin prophylaxis without evidence of increased mortality risk from hemorrhage. A key clinical question in the United States is whether heparin prophylaxis should be expanded to patients hospitalized for cesarean delivery or an antepartum indication. Some experts, including us, support expanded heparin prophylaxis. Evidence supporting heparin prophylaxis includes (1) demonstration of safety and efficacy in the United Kingdom, (2) that mechanical prophylaxis-the primary alternative to heparin-has major limitations outside the immediate perioperative setting, and (3) that hospitalized cesarean and antepartum patients are at high relative risk of events. Experts against broader heparin prophylaxis cite concerns related to safety, efficacy, and cost. This expert review focused on whether heparin prophylaxis should be routinely used during antepartum hospitalizations and after cesarean delivery. First, we review the differences in major society guidelines. Second, we review arguments for and against broader heparin prophylaxis. Third, we discuss what future research may be most likely to further inform best practices. Fourth, we review practical clinical considerations with heparin prophylaxis, including access to neuraxial anesthesia. Given the best available data, we concluded that expanding heparin prophylaxis represents a modest intervention with the potential to meaningfully reduce venous thromboembolism mortality.

Keywords: deep vein thrombosis; maternal morbidity; maternal mortality; obstetrical thromboembolism; pulmonary embolism; thromboembolism prophylaxis.

Publication types

  • Review

MeSH terms

  • Anticoagulants / therapeutic use
  • Female
  • Heparin / therapeutic use
  • Humans
  • Intermittent Pneumatic Compression Devices
  • Maternal Mortality
  • Practice Guidelines as Topic
  • Pregnancy
  • Pregnancy Complications, Hematologic / prevention & control*
  • Venous Thromboembolism / prevention & control*


  • Anticoagulants
  • Heparin