U.S. flag

An official website of the United States government

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.

Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006-.

Cover of Drugs and Lactation Database (LactMed®)

Drugs and Lactation Database (LactMed®) [Internet].

Show details


Last Revision: August 16, 2021.

Estimated reading time: 1 minute

CASRN: 9041-08-1

image 53787074 in the ncbi pubchem database

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.[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.


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

Disclaimer: Information presented in this database is not meant as a substitute for professional judgment. You should consult your healthcare provider for breastfeeding advice related to your particular situation. The U.S. government does not warrant or assume any liability or responsibility for the accuracy or completeness of the information on this Site.

Copyright Notice

Attribution Statement: LactMed is a registered trademark of the U.S. Department of Health and Human Services.

Bookshelf ID: NBK501704PMID: 30000764


Related information

Similar articles in PubMed

See reviews...See all...

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...