Enoxaparin (VTE in Pregnancy)

How it works

Potentiates antithrombin to inhibit factor Xa (and to a lesser extent thrombin), reducing thrombin generation and clot propagation.

Prescribing in practice

• Low molecular weight heparin is the preferred anticoagulant in pregnancy because, unlike warfarin and direct oral anticoagulants, it does not cross the placenta and avoids fetal harm.
• Dosing is weight-based and should be adjusted as maternal weight changes; renal impairment requires caution and reduced exposure.
• Plan timing of doses around delivery and regional anaesthesia to limit bleeding and spinal haematoma risk, in line with obstetric anaesthetic guidance.

Monitoring

Routine anti-Xa monitoring is not needed for most patients but is considered at extremes of body weight or in significant renal impairment, alongside platelet awareness.

Counselling the patient

• Learn the subcutaneous injection technique and rotate sites; some bruising at the site is common.
• Report unusual bleeding, and stop dosing and contact the maternity team when labour begins as advised.
• Do not miss doses, as continued prophylaxis is important throughout the agreed period including after delivery.

Evidence & guidelines

RCOG guidance recommends low molecular weight heparin for the prevention and treatment of venous thromboembolism in pregnancy and the puerperium.