Although heparin itself has not been studied, low molecular weight heparins (e.g., dalteparin, enoxaparin) are not excreted into breastmilk in clinically relevant amounts. Because heparin has an even higher molecular weight of 3000 to 30,000 daltons, it would not be expected to be appreciably excreted into breastmilk or absorbed by the infant. No special precautions are required.[1,2]