Ask Dr. Stephan Moll

These questions have been submitted by folks on the mailing list and answered by Dr. Moll, Director of the Thrombophilia Program at the Carolina Cardiovascular Biology Center, Department of Medicine, Division of Hematology-Oncology, UNC Chapel Hill (North Carolina, USA). Why am I doing this?

30. Breastfeeding and Coumadin®

Q: "I was treated with Lovenox® during my pregnancy for a DVT. I am now breast-feeding. My ob-gyn told me that I should stay on Lovenox for the 6 weeks postpartum because coumadin might appear in the breast milk."

A: Coumadin (warfarin) does not cross over into the breast milk. Women who need anticoagulants in the postpartum period and want to breast-feed can be on Coumadin (warfarin). I usually prefer Coumadin (warfarin) in the postpartum period, to avoid the risk of osteoporosis associated with Lovenox® and other low molecular weight heparins.

Warfarin (Coumadin) is not detectable in the breast milk of mothers who take warfarin (coumadin). It is therefore safe to take in the breast-feeding woman. Since only a limited number of women on warfarin have been studied, these data can not exclude occasional passage of small amounts of warfarin into breast milk, but such doses are unlikely to cause bleeding in the newborn. However, it may be prudent to check coagulation studies in the newborn at risk for vitamin K deficiency, such as the premature born baby, before advising breast-feeding to mothers taking warfarin (coumadin).

There are very limited data in the medical literature on other coumarin drugs (see Q/A 26), such as Phenprocoumon (Marcumar®, Falithrom®, etc), or Acenocoumarol (= Sinthrome®, Sintrom®). It is therefore not known, whether they are also safe. Phenindione and Anisindione (see Q/A 26) do appear in breast-milk and should therefore not be used by the nursing mother.

References:

1. Clark SL, Porter TF, West FG. Coumarin derivatives and breast-feeding. Obstetrics & Gynecology 2000; 95:938-40.
2. Orme ML, Lewis PJ, de Swiet M, et al. May mothers given warfarin breast-feed their infants? Br Med J 1977;1:1564-5.
3. De Swiet M, Lewis PJ. Excretion of anticoagulants in human milk. New England Journal of Medicine 1977; 297:1471.

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