From the Guidelines
Warfarin (Coumadin) is safe for use during breastfeeding, as it is polar, nonlipophilic, and highly protein-bound, making it unlikely to be excreted into breast milk and induce an anticoagulant effect in the breast-fed infant. The American College of Chest Physicians evidence-based clinical practice guidelines support the use of warfarin in lactating women, citing that there have been no reports of harmful effects to breast-feeding infants and that warfarin is not detected in breast milk 1, 2. Additionally, the guidelines recommend continuing the use of warfarin, acenocoumarol, or UFH in lactating women who wish to breast-feed, with a Grade 1A recommendation 3.
Key points to consider:
- Warfarin's properties make it unlikely to be excreted into breast milk, and studies have shown undetectable drug levels in breast milk and normal coagulation profiles in infants of lactating women taking warfarin 2, 4
- The American Academy of Pediatrics classifies warfarin as compatible with breastfeeding, and alternative anticoagulants like low molecular weight heparins (such as enoxaparin) are also considered safe during breastfeeding 2, 4
- Mothers taking warfarin should still inform their healthcare providers about breastfeeding status, and the infant should be monitored for any unusual bleeding or bruising as a precaution, with regular INR monitoring for the mother continuing as normally prescribed 2, 4
Overall, the evidence supports the safety of warfarin use during breastfeeding, and mothers taking warfarin can be reassured that it is unlikely to harm their breast-fed infants.
From the FDA Drug Label
Based on very limited published data, warfarin has not been detected in the breast milk of mothers treated with warfarin The same limited published data report that some breast-fed infants, whose mothers were treated with warfarin, had prolonged prothrombin times, although not as prolonged as those of the mothers. The decision to breast-feed should be undertaken only after careful consideration of the available alternatives Women who are breast-feeding and anticoagulated with warfarin should be very carefully monitored so that recommended PT/INR values are not exceeded.
Warfarin is likely safe during breastfeeding, but close monitoring is recommended. The decision to breastfeed should be made after careful consideration of the available alternatives, and women who are breastfeeding and anticoagulated with warfarin should be carefully monitored to avoid exceeding recommended PT/INR values 5.
From the Research
Safety of Warfarin during Breastfeeding
- Warfarin is considered safe for use during breastfeeding, as it is not excreted into breast milk 6, 7.
- Studies have shown that warfarin can be safely given to women requiring therapeutic anticoagulation postpartum, without posing a risk to the breastfed infant 6, 8.
- However, it is essential to monitor the international normalized ratio (INR) closely, as warfarin dose requirements may change during the postpartum period, especially in breastfeeding women 8.
- Other anticoagulants, such as heparins, are also safe for use during breastfeeding, but warfarin is the only oral anticoagulant recommended for breastfeeding women 9.
- In cases of warfarin overdose, the breastfed infant should be evaluated and tested for ill effects, but the risk of harm is considered low 10.