Low Molecular Weight Heparin Pregnancy: B

Enoxaparin (Vascular)

Brand names: Clexane

Adult dose

Dose: Therapeutic: 1.5 mg/kg once daily or 1 mg/kg twice daily SC; Prophylactic: 40 mg once daily SC

Route: subcutaneous injection

Frequency: once or twice daily (therapeutic); once daily (prophylactic)

Max: 1.5 mg/kg/day (therapeutic)

Preferred over UFH for most VTE indications; syringe pre-filled; do NOT expel air bubble before injection

Dose: 1.5 mg/kg

Route: subcutaneous

Frequency: once daily (therapeutic); 0.5 mg/kg BD for neonates

Max: 1.5 mg/kg/day

Concentration: 100 mg/mL or 150 mg/mL prefilled syringes mg/ml

Neonates: 1.5 mg/kg BD; 2 months–18 years: 1 mg/kg BD; anti-Xa target: 0.5–1.0 units/mL (4h post-dose)

Renal

Reduce to 1 mg/kg once daily if eGFR <30 ml/min; anti-Xa monitoring required

Hepatic

Use with caution in severe hepatic impairment

Paediatric weight-based calculator

Patient weight (kg)

Neonates: 1.5 mg/kg BD; 2 months–18 years: 1 mg/kg BD; anti-Xa target: 0.5–1.0 units/mL (4h post-dose)

Anti-Xa monitoring NOT routinely required for standard doses — measure 4h post-dose in renal impairment, extreme weights, pregnancy
HIT: drop in platelets >50% or to <100 × 10⁹/L after heparin exposure — switch to argatroban/danaparoid
Protamine only partially reverses LMWH (neutralises anti-IIa activity completely but only ~60% anti-Xa)

Reference: BNFc; BNF 86; BCSH guidelines; NICE NG158. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

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