Effects of low-dose aspirin on uterine and fetal blood flow during pregnancy: results of a randomized, placebo-controlled, double-blind trial

Objective This study was conducted to evaluate uteroplacental and fetal hem odynamics in fetuses exposed to lour-dose aspirin (100 mg/d). Design Randomized, placebo-controlled, double-blind trial. Subjects The study protocol included singleton pregnancies of less than 20 gestational weeks at risk for preeclampsia or fetal growth restriction. Exc lusion criteria were diabetes mellitus, pre-existing proteinuric hypertensi on or fetal malformations. Forty-three pregnant women were randomly, alloca ted to daily treatment with 100 mg aspirin (II = 22) or placebo (II = 21). Methods Pulsed Doppler measurements of the uterine artery fetal middle cere bral artery, fetal aorta, ductus arteriosus and atrioventricular valves wer e performed longitudinally at 14 day intervals starting front 18 gestationa l weeks until delivery Results were expressed as group medians (aspirin vs. placebo) and were analyzed by Mann/Whitney U-test. Results There was no difference in uterine, umbilical, aortic, middle cereb ral and ductus arteriosus blood flow between tbe aspirin group and controls . Medial? ductal peak flow, velocities increased with gestational age in bo th groups, brit differences between groups did not reach significance. In t he third trimester of pregnancy, ductal peak velocities > 140 cm/s were occ asionally observed in both groups. However, end diastolic velocities > 35 c m/s or atrioventricular valve regurgitation never occurred. Conclusions Daily administration of low-dose aspirin during the second and third trimesters of pregnancy does not alter. uteroplacental ol fetoplacent al hemodynamics and does not cause moderate or severe constriction of the d uctus arteriosus.