Prophylactic Dosing of Lovenox (Enoxaparin) in Pregnancy

The standard prophylactic dose of Lovenox (enoxaparin) in pregnancy is 40 mg subcutaneously once daily for most pregnant patients. 1

Standard Dosing Guidelines

The recommended prophylactic dose of enoxaparin for most pregnant women is 40 mg subcutaneously once daily 2, 1
Enoxaparin is the preferred thromboprophylactic agent in pregnancy due to better bioavailability, longer half-life, more predictable anticoagulation effect, less bleeding risk, and lower risk of heparin-induced thrombocytopenia and osteopenia 2, 3
Studies have confirmed that a dose of 40 mg once daily throughout pregnancy provides satisfactory anti-factor Xa levels and appears effective in preventing venous thromboembolism 4

For pregnant women with class III obesity (BMI ≥40 kg/m²), consider intermediate dosing of 40 mg subcutaneously every 12 hours or weight-based dosing of 0.5 mg/kg subcutaneously every 12 hours 2, 1
Weight-based prophylactic dosing of 0.5 mg/kg subcutaneously every 12 hours in morbidly obese women results in anti-Xa levels more often within the desired prophylactic target range compared to fixed-dose regimens 2
For pregnant women with mechanical heart valves requiring therapeutic anticoagulation, a higher dose of 1 mg/kg twice daily is recommended, with dose adjustments based on anti-Xa levels 2, 5

For standard prophylactic dosing (40 mg daily), routine monitoring of anti-Xa levels is generally not required 1, 4
For therapeutic dosing or in special populations (obesity, renal impairment), anti-Xa monitoring should be performed to ensure appropriate levels 1, 6
Target anti-Xa levels for prophylactic dosing are typically between 0.2-0.5 IU/mL, measured 4-6 hours after injection 1
For therapeutic dosing, target peak anti-Xa levels are 0.5-1.0 U/mL measured 4-6 hours after injection 2, 6

Prophylactic enoxaparin should be discontinued 12-24 hours before planned induction of labor or cesarean delivery 2, 1
Enoxaparin can be resumed 4-12 hours after delivery, depending on the mode of delivery and bleeding risk 2, 1
For patients who received neuraxial anesthesia, prophylactic doses may be started 4 hours after catheter removal but not earlier than 12 hours after the block was performed 1

Underdosing is common in obesity class ≥2 when using standard LMWH doses 1
Consider unfractionated heparin instead of enoxaparin in patients with significant renal disease 1
Higher heparin requirements should be anticipated in the third trimester because of an increase in heparin-binding proteins 2
Bleeding risk is dose-dependent but generally low (approximately 2%) with prophylactic dosing 3
Heparin-induced thrombocytopenia is very rare with enoxaparin, and bone resorption is not clinically significant 3

For pregnant women with thrombophilia requiring prophylaxis during assisted reproductive technology procedures, enoxaparin 40 mg daily is typically started at the beginning of ovarian stimulation, withheld 24-36 hours prior to oocyte retrieval, and resumed following retrieval 2
For treatment of deep vein thrombosis in pregnancy, either 1 mg/kg twice daily or 1.5 mg/kg once daily regimens appear to be equally effective 7

Enoxaparin does not cross the placenta and is considered safe for the fetus, making it the anticoagulant of choice during pregnancy 3.