A Pilot Randomized Trial Comparing the Effects of 80 versus 160 mg of Aspirin on Midtrimester Uterine Artery Pulsatility Index in Women with a History of Preeclampsia

ObjectiveTo compare the effects of 80 mg and 160 mg of aspirin, initiated in the first trimester of pregnancy, on mid-trimester uterine artery pulsatility index (UtA-PI) in women with a history of preeclampsia.MethodsWe performed a pilot double-blind randomized controlled trial. Pregnant women with a history of preeclampsia were recruited between 10^0/7 and 13^6/7 weeks gestation and randomly assigned to take either 80 or 160 mg of aspirin daily at bedtime from randomization to 35^6/7 weeks gestation. The primary outcome was mean UtA-PI at 22–24 weeks. Secondary outcomes included the rate of fetal growth restriction and preeclampsia, stratified as term (≥37 weeks), preterm (<37 weeks), and early-onset (<34 weeks) preeclampsia.ResultsA total of 107 participants were randomized, including 41 (38%) with a history of preterm preeclampsia and 16 (15%) with a history of early-onset preeclampsia. We observed no significant difference in mean UtA-PI at 22–24 weeks between the 2 groups (0.97; 95% CI 0.88–1.05 vs. 0.97; 95% CI 0.88–1.07, P = 0.9). The rates of fetal growth restriction (8% vs. 2%; P = 0.20); preeclampsia (12% vs. 15%; P = 0.78), preterm preeclampsia (4% vs. 2%; P = 0.56), and early-onset preeclampsia (0% vs. 2%; P = 0.52) were similar in both groups. No serious adverse events associated with the study treatment were reported.ConclusionWe observed no significant difference in UtA-PI between the two doses of aspirin, but we observed low rates of fetal growth restriction and preterm and early-onset preeclampsia (all less than 5%). The benefits of aspirin for the prevention of preterm preeclampsia is probably not related to the improvement of deep placentation alone.