The high molecular weight of both standard or non-fractionated Heparin, and, so-called low molecular weight Heparin makes excretion into breast milk extremely difficult. Dalteparin has been shown not to be excreted into breast milk . In addition, Heparins are inactivated in the GE tract where they are not absorbed which is reason to have a nil oral bioavailability. Absence of anti-clotting activity in breastfed infants has been shown after treatment of the mother with Enoxaparin. Risk of Heparin-induced Thrombocytopenia or Osteoporosis in the mother is lower with low weight Heparins. Eleventh WHO Model List of Essential Drugs 2002: Compatible with breastfeeding.