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Use of low molecular mass heparin (enoxaparin) in newborn infants: a prospective cohort study of 62 patients
  1. W Streif1,
  2. G Goebel2,
  3. A K C Chan3,
  4. M P Massicotte4
  1. 1Department of Pediatrics, University of Innsbruck, Austria
  2. 2Department of Biostatistics and Documentation, University of Innsbruck
  3. 3Department of Pediatrics, McMaster University, Hamilton, Canada
  4. 4The Hospital for Sick Children, Toronto, Canada
  1. Correspondence to:
    Dr Streif, Department of Pediatrics, University of Innsbruck, 6020 Innsbruck, Austria;


Objective: To detail low molecular mass heparin (enoxaparin) use in the first few months of life.

Design: Prospective, consecutive cohort of unselected newborn infants.

Methods: Newborn infants were divided into groups by gestational age, underlying condition, hepatic and renal function, thrombocytopenia, and prothrombin time (PT/INR). Groups were analysed with respect to many aspects of enoxaparin treatment using multivariate methods.

Results: Sixty two newborn infants received enoxaparin representing 5.39 treatment years. Thromboembolic events (TEs) occurred predominantly in the lower and upper venous system in the presence of indwelling catheters (69%). Preterm infants required longer than full term infants to achieve an anti-(factor Xa) level in the target range (six versus two days). Preterm infants required higher doses of enoxaparin than full term infants to maintain anti-(factor Xa) levels in the target range (2.1 v 1.7 mg/kg/12 h). Infants with congenital heart disease (CHD) required less enoxaparin than those without CHD to maintain an anti-(factor Xa) level in the target range (1.7 v 2.1 mg/kg/12 h). Impaired renal and liver function influenced the number of dose changes needed (three versus one a month). Complete or partial resolution of TE was accomplished in 59% of newborn infants. Four infants developed major bleeds (1.2% per patient year). Recurrent TE and clot extension occurred in three infants (0.9% per patient year).

Conclusions: Preterm infants are more difficult to treat with enoxaparin than full term infants. Enoxaparin appears to be an alternative to treatment with standard heparin or no treatment.

  • thrombosis
  • thromboembolism
  • low molecular mass heparin
  • enoxaparin
  • CHD, congenital heart disease
  • HSC, The Hospital For Sick Children, Toronto, Canada
  • INR, international normalised ratio
  • LMMH, low molecular mass heparin
  • TE, thromboembolic event
  • US, ultrasonography

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