The Basics
What is Warfarin?
Used to treat people who have had a previous blood clot.
Brand names for Warfarin
Coumadin
How Warfarin is classified
Anticoagulants
Warfarin During Pregnancy
Warfarin pregnancy category
Category N/ANote that the FDA has deprecated the use of pregnancy categories, so for some medications, this information isn’t available. We still think it’s useful to list historical info, however, given what a common proxy this has been in the past.
What we know about taking Warfarin while pregnant
COUMADIN is contraindicated in women who are pregnant except in pregnant women with mechanical heart valves, who are at high risk of thromboembolism, and for whom the benefits of COUMADIN may outweigh the risks . COUMADIN can cause fetal harm. Exposure to warfarin during the first trimester of pregnancy caused a pattern of congenital malformations in about 5% of exposed offspring. Because these data were not collected in adequate and well-controlled studies, this incidence of major birth defects is not an adequate basis for comparison to the estimated incidences in the control group or the U.S. general population and may not reflect the incidences observed in practice. Consider the benefits and risks of COUMADIN and possible risks to the fetus when prescribing COUMADIN to a pregnant woman. Adverse outcomes in pregnancy occur regardless of the health of the mother or the use of medications. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.
Taking Warfarin While Breastfeeding
What are recommendations for lactation if you're taking Warfarin?
Because of the very low milk levels with warfarin doses up to at least 12 mg daily, amounts ingested by the infant are small. No adverse reactions in breastfed infants have been reported from maternal warfarin use during lactation, even with a dose of 25 mg daily for 7 days. There is a consensus that maternal warfarin therapy during breastfeeding poses little risk to the breastfed infant.[1][2][3][4][5] No special precautions are necessary.
Maternal / infant drug levels
Because of the very low milk levels with warfarin doses up to at least 12 mg daily, amounts ingested by the infant are small. No adverse reactions in breastfed infants have been reported from maternal warfarin use during lactation, even with a dose of 25 mg daily for 7 days. There is a consensus that maternal warfarin therapy during breastfeeding poses little risk to the breastfed infant.[1][2][3][4][5] No special precautions are necessary.
Possible effects of Warfarin on milk supply
Relevant published information was not found as of the revision date.
Possible alternatives to Warfarin
Acenocoumarol, Dalteparin, Enoxaparin, Heparin.
List of References
Lactation sources: Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK501922/1. Toll LL. Anticoagulant use during breastfeeding. J Hum Lact. 1991;7:193-4. PMID: 1818575
2. Olthof E, De Vries TW. [Breast feeding and oral anticoagulants]. Tijdschr Kindergeneeskd. 1993;61:175-7. PMID: 8266311
3. Clark SL, Porter TF, West FG. Coumarin derivatives and breast-feeding. Obstet Gynecol. 2000;95(6 pt 1):938-40. PMID: 10831996
4. Middeldorp S. How I treat pregnancy-related venous thromboembolism. Blood. 2011;118:5394-400. PMID: 21921048
5. Bates SM, Greer IA, Middeldorp S et al. VTE, thrombophilia, antithrombotic therapy, and pregnancy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest. 2012;141 (2 Suppl):e691S-736S. PMID: 22315276
6. Orme ML, Lewis PJ, De Swiet M et al. May mothers given warfarin breast-feed their infants? Br Med J. 1977;1:1564-5. PMID: 871666
7. McKenna R, Cole ER, Vasan U. Is warfarin sodium contraindicated in the lactating mother? J Pediatr. 1983;103:325-7. PMID: 6410034
8. Ito S, Blajchman A, Stephenson M et al. Prospective follow-up of adverse reactions in breast-fed infants exposed to maternal medication. Am J Obstet Gynecol. 1993;168:1393-9. PMID: 8498418
9. Schindler D, Graham TP. Warfarin overdose in a breast-feeding woman. West J Emerg Med. 2011;12:216-7. PMID: 21691530
Disclaimer: This material is provided for educational purposes only and is not intended for medical advice, diagnosis, or treatment. Consult your healthcare provider with any questions.
