Drug therapy for VTE prophylaxis in pregnancy

Refer patients with multiple VTE risk factors to a specialist; decisions about VTE prophylaxis and duration in pregnancy are complex and depend on the number and nature of the patient’s VTE risk factors.

If VTE prophylaxis is given to pregnant patients, low molecular weight heparin (LMWH) or unfractionated heparin (UFH) must be used. Appropriate anticoagulant options for use while breastfeeding include LMWH and warfarin, but not direct-acting oral anticoagulants (DOACs).

Patients who receive prophylaxis during pregnancy should continue their anticoagulation for 6 weeks postpartum. Other patients (such as a patient whose only risk factor is a history of a single provoked VTE), may only require 6 weeks of postpartum prophylaxis (and not during pregnancy)Royal College of Obstetricians and Gynaecologists (RCOG), 2015.

Stop prophylactic doses of LMWH at the onset of labour. For pregnant patients receiving a therapeutic dose of LMWH, a scheduled delivery with prior discontinuation of the anticoagulant therapy is recommendedBates, 2018.

Excessive blood loss (more than 1000 mL) is a risk factor for the development of VTE. Although VTE prophylaxis should be withheld during a postpartum haemorrhage, when the haemorrhage is controlled, consider starting VTE prophylaxis for the postpartum period—seek specialist adviceScottish Intercollegiate Guidelines Network (SIGN), Updated 2014.

The daily risk of VTE postpartum is 3 to 5 times greater than during the antenatal period, so reassess patients shortly after they give birth. If their clinical condition changes, they can start or change anticoagulant therapy (eg following an emergency caesarean section, see VTE prophylaxis for surgical patients in hospital). The harm–benefit balance for VTE prophylaxis changes postpartum because of the increased risk of VTE and because some serious adverse anticoagulant effects (eg fetal haemorrhage, placental haemorrhage, spinal haematoma following epidural) are no longer a consideration.