LDA and LMWH vs LDA Alone in High-risk Patients for Preeclampsia Prevention

This is a prospective, randomized, single-center, open-label trial conducted at the First Obstetrics and Gynecology Clinic of Alexandra Hospital, Athens, Greece. One hundred pregnant women at high risk of preeclampsia (risk \>1:150) will be randomly allocated 1:1 to receive either 160mg aspirin daily (n=50) or 160mg aspirin plus weight-adjusted therapeutic doses of LMWH (tinzaparin 4,500-8,000 IU daily based on weight) (n=50) initiated before 16 weeks gestation until 36 weeks. Risk assessment will be performed using the internationally recognized FMF (Fetal Medicine Foundation) model, combining first trimester ultrasound examination, biochemical markers, and individual medical history. The primary outcome is the incidence of preeclampsia. Secondary outcomes include development of early preeclampsia (\<34 weeks), gestational hypertension, HELLP syndrome, spontaneous preterm labor, intrauterine growth restriction, placental abruption, and various neonatal outcomes. Blood samples will be collected at 20-24, 32-34, and 36 weeks to measure biomarkers including PlGF, sFlt-1, E-Selectin, IL-1β, IL-6, IL-10, TNF-α, sFlt-1/PlGF ratio, and systemic immune-inflammation index (SII). Regular telephone follow-up will be conducted to monitor adherence and adverse events.