Excretion of low molecular weight heparin in human milk

Abstract

AIMS: The excretion of low molecular weight heparin (LMWH) in breast milk was investigated in 15 lactating mothers after Caesarean section. METHODS: Blood and milk samples were collected before and 3-4 h after once daily routine subcutaneous injection of 2500 IU dalteparin. Anti-Xa activity was measured by an assay utilizing prolonged clotting times in plasma or breast milk as an index of LMWH activity. RESULTS: Plasma anti-Xa activities ranged from 0.074 to 0.308 IU ml(-1) of plasma. Anti-Xa activities in breast milk ranged from < 0.005-0.037 IU ml(-1) of milk. This is equivalent to a milk/plasma ratio of < 0.025-0.224. CONCLUSIONS: Therefore, it appears highly unlikely that puerperal thromboprophylaxis with LMWH has any clinically relevant effect on the nursing infant.