Skip to Main Content


Long-term therapeutic anticoagulation during pregnancy is necessary for:


  • History of venous thromboembolism in prior pregnancy
  • History of recurrent thromboembolism
  • Thrombophilias
  • Mechanical heart valve prosthesis
  • Certain medical conditions (Eisenmenger, severe heart failure, chronic atrial fibrillation)

Table Graphic Jump Location
Favorite Table | Download (.pdf) | Print
Antithrombotic Agents in Pregnancy
Unfractionated heparin (UFH)
  • Does not cross placenta
  • Bone demineralization with long-term use
  • Risk of HIT
  • Does not cross into breast milk in significant amounts (safe with breast-feeding)
  • Reversal of anticoagulation for delivery seldom necessary
  • If reversal is needed (usually for Cesarean delivery), titrate protamine
Low-molecular-weight heparin (LMWH)
  • Does not cross placenta
  • Bone demineralization may occur with long-term use
  • Does not cross into breast milk in significant amounts (safe with breast-feeding)
  • Should be converted to UFH at 36 weeks gestation
  • In an emergency situation reversal is not complete (discuss with hematologist dose of protamine)
  • Substitution of LMWH for warfarin in patients with mechanical heart valves remains controversial
  • Freely crosses placental barrier
  • Fetal effects appear to be dose related rather than INR related
  • Fetal hemorrhage may occur
  • Neonatal hemorrhage may occur (if patient has not been converted to UFH, delivery should be via Cesarean section)
  • Does not cross into breast milk in significant amounts (safe with breast-feeding)
  • Use is limited to patients with mechanical heart valves
  • Should not be used between 6 and 13 weeks of gestation to minimize teratogenic effects
  • Dose should be kept under 5 mg daily
  • Switch to UFH at 36 weeks
  • If emergency delivery is necessary, both mother and newborn should receive FFP to reverse drug effects (vitamin K onset is too slow in this clinical setting)

Anticoagulation should be restarted 6 hours following vaginal delivery and 12 hours following Cesarean delivery if there are no clinical signs of ongoing hemorrhage.

Table Graphic Jump Location
Favorite Table | Download (.pdf) | Print
Anesthesia Considerations in the Anticoagulated Parturient
Labor analgesia
  • Neuraxial analgesia should not be attempted in an actively anticoagulated patient
  • Follow neurological status throughout labor and postpartum for spinal hematoma
  • Neuraxial analgesia in patients on prophylactic UFH is safe
  • UFH in intermediate and therapeutic dose should be stopped for 6 h and a normal aPTT documented before neuraxial analgesia is attempted
  • Check platelet count if patient has received UFH for at least 4 days
  • Prophylactic LMWH should be stopped for at least 12 h
  • Intermediate and therapeutic LMWH should be stopped for at least 24 h
  • Warfarin should be stopped for at least 5 days and a normal PT/INR should be documented; furthermore, time should be allowed for substitute antithrombotic agents to wear off (bleeding risk increases in patients recently converted from warfarin to UFH or LMWH)
Vaginal deliveryRisk of bleeding in mother may be increased
  • Evaluate patient thoroughly for potential intrapartum and postpartum hemorrhage
  • Establish adequate venous access
  • Consider reversing heparin effects with protamine
  • Have 4 U PRBC cross-matched
  • Evaluate and review airway throughout labor
Cesarean section
  • Neuraxial anesthesia should ...

Want remote access to your institution's subscription?

Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.


About MyAccess

If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.

Subscription Options

AccessAnesthesiology Full Site: One-Year Subscription

Connect to the full suite of AccessAnesthesiology content and resources including procedural videos, interactive self-assessment, real-life cases, 20+ textbooks, and more

$995 USD
Buy Now

Pay Per View: Timed Access to all of AccessAnesthesiology

24 Hour Subscription $34.95

Buy Now

48 Hour Subscription $54.95

Buy Now

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.