Anticoagulant treatment of venous thromboembolism in pregnant women

Venous thromboembolism (VTE), in particular pulmonary embolism (PE), remains the leading cause of death among pregnant women. Low-molecular-weight heparin (LMWH), with preference for therapeutic doses given twice daily according to European guidelines, is the drug of choice for the treatment of VTE in pregnancy and the puerperium. The recommended therapeutic dose is calculated on early pregnancy body weight. Evidence to support anti-Xa monitoring in pregnancy is weak. Unfractionated heparin (UFH) with multiple activated partial thromboplastin time measurements is still used in the acute treatment of high-risk PE. American experts have suggested considering initial outpatient therapy over hospital admission also in pregnant women with low-risk acute VTE, but European experts suggest adopting such a strategy selectively, for example in isolated distal leg thrombosis. Scheduled delivery with prior discontinuation of anticoagulant therapy in pregnant women who received a therapeutic dose of LMWH is suggested with the restart of therapy 4–6 h after a vaginal birth and 6–12 h after a cesarean delivery. It is recommended that UFH, LMWH, warfarin, acenocoumarol, or fondaparinux, but not direct-acting oral anticoagulants, should be used in breastfeeding women. This review summarizes the key messages from current guidelines mainly based on low-quality evidence and expert consensus.