Monitoring LMWHs in pregnancy

Use of LMWH in pregnancy 3rd trimester
Patient weight q2 weeks
Platelet count q2 weeks
Hematocrit q2 weeks
Serum creatinine/CrCl q2 weeks and adjust LMWH dose if needed
Trough antiXa level q1 month if CrCl > 60ml/min or q2 weeks if < 60ml/min
Goal: <0.5 units/ml (adjust LMWH dose or dosing interval if needed)
Peak antiXa level q2 weeks (check 4 hrs after dose)
Goal: 0.5-1 units/ml (for q12h dosing of LMWH)
Adjust LMWH dosing if needed, according to suggestions below





LMWH dosage adjustments based on peak antiXa levels

[from Monagle P et al.  Chest 2001; 119 (suppl 1): 344-370]

Peak antiXa level (units/ml) Hold next dose Dosage change Next antiXa level
<0.35 No Increase 25% 4hrs after next dose
0.35-0.49 No Increase 10% 4hrs after next dose
0.5-1 No None Next day, then within 1 week
1.1-1.5 No Decrease 20% Before next dose
1.6-2 For 3 hours Decrease 30% Before next dose and 4hrs after next dose
>2 Until antiXa level <0.5 Decrease 40% Before next dose and q12h until antiXa level <0.5