Aspirin therapy and risk of pregnancy loss in patients with ET

The live birth rate was 72%, with most of the unintentional fetal losses occurring in the first trimester (24%). Fetal complications other than pregnancy loss were reported in 7% of patients, including preterm birth (3%), intrauterine growth restriction (3%), and neonatal intensive care admission (2%). Maternal complications occurred in 13% of patients, and included major hemorrhage (7%), preeclampsia (6%), venous thrombosis (1%), hemolysis with elevated liver enzymes and low platelets (1%), and placental abruption (0.5%).

Treatment with aspirin (n = 135) when compared with no treatment or treatment other than aspirin (n = 65) reduced the risk of pregnancy loss (16% vs 49%; p < 0.01) and first-trimester pregnancy loss (14% vs 45%; p < 0.01) in patients with ET, including lower incidences of first-trimester pregnancy loss in patients with mutated JAK2 (18% vs 50%; p < 0.01) or mutated CALR (8% vs 43%; p < 0.01). This suggests aspirin should be considered a standard preventive measure in managing pregnancies in patients with ET.

Aspirin use was also associated with a lower incidence of maternal venous thrombosisduring pregnancy in patients with ET (0% vs 3%, p = 0.03), reinforcing its dual protective role in both fetal and maternal outcomes.