Drug Levels and Effects:

Summary of Use during Lactation:

Because of the low levels of dalteparin in breastmilk and its large molecular weight of 2000 to 9000 daltons, amounts ingested by the infant are small and it would not be expected to be absorbed from breastmilk by the infant. No special precautions are required.

Drug Levels:

Maternal Levels.

In two women receiving subcutaneous dalteparin 5000 IU daily and 10,000 IU daily, respectively, dalteparin was undetectable in breastmilk.[1]

Anti-Xa activity (a measurement of enoxaparinanticoagulantactivity) was measured in the milk of 15 patients before and 3 to 4 hours after 4 to 8 days at a dosage of 2500 IU/day subcutaneously. Anti-Xa activity in milk ranged from less than 5 to 37 IU/L which was 2.5 to 22.4% of the simultaneous maternal plasma anti-Xa activity.[2]

Infant Levels.

Relevant published information was not found as of the revision date.

Effects in Breastfed Infants:

Although not clearly stated, it appears that 15 neonates were breastfed during maternal dalteparin use in one study with no adverse effects reported.[2]

In another study, one mother breastfed her infant for 20 days starting at 7 weeks of age while taking subcutaneous dalteparin 5000 IU subcutaneously twice daily with no adverse effects to her infant.[3]

Possible Effects on Lactation:

Relevant published information was not found as of the revision date.

Alternate Drugs to Consider:



1. Harenberg J, Leber G, Zimmermann R et al. [Prevention of thromboembolism with low-molecular weight heparin in pregnancy]. Geburtshilfe Frauenheilkd. 1987;47:15-8. PMID:3569823
2. Richter C, Sitzmann J, Lang P et al. Excretion of low molecular weight heparin in human milk. Br J Clin Pharmacol. 2001;52:708-10. PMID:11736885
3. Lindhoff-Last E, Willeke A, Thalhammer C et al. Hirudin treatment in a breastfeeding woman. Lancet. 2000;355:467-8. PMID:10841132

Substance Identification:

Substance Name:


Drug Class:

  • Low Molecular Weight Heparin

  • Administrative Information:

    LactMed Record Number:


    Last Revision Date:

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