Heparin and breastfeeding

Low molecular weight heparins (e.g., dalteparin, enoxaparin) are not excreted into breastmilk in clinically relevant amounts (1):

• any heparin (low molecular weight (LMWH), or unfractionated) can be used during breastfeeding (2)
  
  • 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
    
    
• dalteparin can be used during breastfeeding. Infant monitoring is still required (2)
  • as a precaution, infants should be monitored for rare bruising on the skin or any unusual bleeding
  • monitoring the infant will quickly pick up any potential issues, but further investigation is usually required before the cause can be attributed to the medicine
    
    
• enoxaparin can be used during breastfeeding. Infant monitoring is still required (2)
  • as a precaution, infants should be monitored for rare bruising on the skin or any unusual bleeding
  • monitoring the infant will quickly pick up any potential issues, but further investigation is usually required before the cause can be attributed to the medicine

Reference:

• Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006-. Heparin. [Updated 2020 Nov 16]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK500921/
• NHS Specialist Pharmacy Service (January 2024). Using heparins during breastfeeding