Table 1.

Thromboprophylaxis in pregnancy and lactation.^84–89

Anticoagulant	Antepartum considerations	Peripartum considerations	Postpartum considerations	Usual dose
Unfractionated heparin	No placental transfer If close to delivery, UFH may be preferred Use pre-filled syringes or preservative free formulations (avoid preparations containing benzyl alcohol as this preservative has been associated with gasping syndrome/fatal toxic syndrome in premature infants)	Check PTT/aPTT before neuraxial analgesia Can perform neuraxial analgesia 4-6 hours after last dose Can administer prophylaxis 1 hour after neuraxial analgesia	Can initiate 1 hour after neuraxial analgesia or catheter removal (if adequate hemostasis) Lactation: Compatible Infant monitoring: - Rare skin bruising - Blood in urine, emesis, or stool	5,000 units SC every 8-12 hours
Low molecular weight heparin Enoxaparin Dalteparin Tinzaparin		Can perform neuraxial analgesia 10-12 hours after last dose Can administer prophylaxis 4-6 hours after neuraxial analgesia	Can initiate 12 hours after neuraxial analgesia or 4 hours after catheter removal, whichever is greater (if adequate hemostasis) Lactation: Compatible Infant monitoring: - Rare skin bruising - Blood in urine, emesis, or stool	Enoxaparin* 40 mg SC every 24 hours Dalteparin* 2,500-5,000 units SC every 24 hours Tinzaparin* 3,500-4,500 units SC every 24 hours
Heparinoid Danaparoid	Pregnancy considerations: Reserved for pregnant people with allergies or adverse reactions to unfractionated and low molecular weight heparins. Danaparoid is the preferred anticoagulant in pregnant people with HIT.  Lactation: Probably compatible.
Factor Xa inhibitor Fondaparinux	Pregnancy considerations: Reserved for pregnant people with allergies or adverse reactions to UFH and LMWH who cannot receive danaparoid.  Lactation: Probably compatible.
Vitamin K antagonist Warfarin	Pregnancy considerations: Contraindicated in pregnancy (except pregnant people with mechanical heart valves or if alternatives not available/appropriate, requiring close monitoring and tailored pharmacotherapy by a specialist) due to teratogenic and fetal toxicity risk. Lactation: Probably compatible.
DOAC (thrombin inhibitor) Dabigatran	Pregnancy considerations: Not recommended for use in pregnant people due to insufficient safety data and potential harm to maternal and fetal conditions. Lactation: Not recommended.
DOAC (Factor Xa inhibitor) Rivaroxaban Apixaban Edoxaban

*Requires dose adjustment based on renal function; higher doses may be considered in obese patients

aPTT: activated partial thromboplastin time; DOAC: direct oral anticoagulant; HIT: heparin-induced thrombocytopenia, LMWH: low molecular weight heparin; PTT: partial thromboplastin time; SC: subcutaneous; UFH: unfractionated heparin