Low-Molecular-Weight Heparin in Preeclampsia: Effects on Biomarkers and Prevention: A Narrative Review

Preeclampsia affects 2-8% of pregnancies globally and remains a leading cause of maternal and perinatal morbidity, with limited preventive options beyond low-dose aspirin. Low-molecular-weight heparin (LMWH) has emerged as a promising therapeutic candidate due to its pleiotropic effects extending beyond anticoagulation, including anti-inflammatory, pro-angiogenic, and placental-protective properties. This comprehensive narrative review examines LMWH's effects on preeclampsia-associated biomarkers and evaluates clinical evidence for its preventive efficacy. LMWH exerts multifaceted effects on disease pathophysiology, including restoration of angiogenic balance through sFlt-1 reduction and PlGF preservation, attenuation of inflammatory responses via decreased TNF-α and IL-6 production, normalization of coagulation parameters, and enhancement of trophoblast invasion and placental vascularization. Clinical trials reveal heterogeneous results, with meta-analyses suggesting significant benefit primarily in high-risk subgroups. Women with previous severe placenta-mediated complications demonstrate relative risk reductions of 40-60% for recurrent preeclampsia with LMWH prophylaxis, particularly when initiated before 16 weeks' gestation. Combination therapy with low-dose aspirin appears to enhance protective effects. However, larger trials in unselected populations have failed to demonstrate significant benefit, highlighting the importance of appropriate patient selection. Current international guidelines reflect this evidence heterogeneity, with most recommending against routine LMWH use while acknowledging potential benefit in selected high-risk populations, particularly those with antiphospholipid syndrome or previous severe early-onset disease. Future research should focus on biomarker-guided patient selection, optimal dosing regimens, and integration with multimodal preventive strategies to maximize therapeutic benefit while minimizing unnecessary interventions.