Low molecular weight heparin (dalteparin) for the treatment of venous thromboembolism in pregnancy.

OBJECTIVE: To evaluate the effect and dose of dalteparin given to pregnant women with acute venous thromboembolism.

DESIGN: An observational study of pregnant women in Norway.

SETTING: Delivery and haematological departments in Norway.

POPULATION: Twenty women, aged 22-41 years, with acute venous thromboembolism verified by objective means.

METHODS: Patients were treated with dalteparin from diagnosis until delivery. Treatment was monitored with anti-activated factor Xa (anti-Xa) activity, and the dose was adjusted to achieve target 0.5-1.0 U/mL 2-3 hours post-injection.

MAIN OUTCOME MEASURES: Anti-Xa activity and side effects.

RESULT: None of the patients suffered recurrent venous thromboembolism or major bleeding complications. In 9 of 13 women starting with conventional dose of dalteparin (100 iu/kg bd), dose escalation was necessary to reach target anti-Xa activity. None of the six women who started with 105-118 iu/kg bd required dose escalation. One woman who started with 133 iu/kg bd required dose reduction. Bioaccumulation of dalteparin was not observed.

CONCLUSION: Our study suggests that dalteparin may be used for the treatment of acute venous thromboembolism in pregnancy. Approximately 10-20% higher doses of dalteparin may be needed as compared with non-pregnant individuals.