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Dalteparin use while Breastfeeding

Medically reviewed by Last updated on Feb 12, 2023.

Drugs containing Dalteparin: Fragmin

Dalteparin Levels and Effects while Breastfeeding

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.[1]

Drug Levels

Maternal Levels. In two women receiving subcutaneous dalteparin 5000 IU and 10,000 IU daily, respectively, dalteparin was undetectable in breastmilk.[2]

Anti-Xa activity (a measurement of anticoagulant activity) was measured in the milk of 15 patients before and 3 to 4 hours after 4 to 8 days at a daily dosage of 2500 IU 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.[3]

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.[3]

In another report, 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.[4]

Effects on Lactation and Breastmilk

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

Alternate Drugs to Consider

Acenocoumarol, Dalteparin, Enoxaparin, Heparin, Rivaroxaban, Warfarin


Bates SM, Rajasekhar A, Middeldorp S, et al. American Society of Hematology 2018 guidelines for management of venous thromboembolism: Venous thromboembolism in the context of pregnancy. Blood Adv. 2018;2:3317–59. [PMC free article: PMC6258928] [PubMed: 30482767]
Harenberg J, Leber G, Zimmermann R, et al. Geburtshilfe Frauenheilkd. 1987;47:15–8. [Prevention of thromboembolism with low-molecular weight heparin in pregnancy] [PubMed: 3569823]
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. [PMC free article: PMC2014571] [PubMed: 11736885]
Lindhoff-Last E, Willeke A, Thalhammer C, et al. Hirudin treatment in a breastfeeding woman. Lancet. 2000;355:467–8. [PubMed: 10841132]

Substance Identification

Substance Name


Drug Class

Breast Feeding



Low Molecular Weight Heparin

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Further information

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