Low molecular weight heparin for the treatment of venous thromboembolism in pregnancy: a case series


*Dr V. A. Rodie, University Department of Obstetrics and Gynaecology, Glasgow Royal Infirmary, Queen Elizabeth Building, 10 Alexandra Parade, Glasgow G31 2ER, UK.


Objectives To assess the use of low molecular weight heparin for the treatment of venous thromboembolism in pregnancy.

Design A prospective observational study.

Setting The maternity units in two university teaching hospitals and one district general teaching hospital.

Population Thirty-six consecutive women presenting with objectively diagnosed venous thromboembolism during pregnancy and the immediate puerperium.

Methods Treatment with the low molecular weight heparin enoxaparin, approximately 1 mg/kg sc, twice daily, based on early pregnancy weight.

Main outcome measures Peak anti-Xa activity (three hours post-injection), alterations in treatment, side effects and the use of regional anaesthesia.

Results In 33 women, the initial dose of enoxaparin provided satisfactory peak anti-Xa activity (median 0.8 u/mL, range 0.44–1.0 u/mL) and was continued. Three women required dose reduction since peak anti-Xa activities were above the therapeutic range (1.2, 1.2 and 1.1 u/mL). No woman developed thrombocytopaenia, haemorrhagic complication or further thromboembolic episode. Two women developed allergic skin reactions on enoxaparin and were changed to tinzaparin. Fifteen women had regional anaesthesia for delivery, with a reduced dose of enoxaparin (40 mg once daily), all without complication.

Conclusions Enoxaparin is a safe and effective treatment for venous thromboembolism during pregnancy and confers a major advantage over unfractionated heparin through its simplified regimen of administration.