THE EFFECT OF LOW-DOSE ASPIRIN ON UMBILICAL ARTERY DOPPLER MEASUREMENTS

OBJECTIVE: Our purpose was to determine if the maternal administration of low-dose (60 mg) aspirin from 24 weeks' gestation until delivery i s associated with significant changes in longitudinal umbilical artery Doppler index values. STUDY DESIGN: Healthy, young nulliparous women with singleton gestations who were enrolled in a double-blind trial of low-dose aspirin for preeclampsia prevention underwent prerandomizati on and monthly postrandomization continuous-wave umbilical artery Dopp ler evaluations. The systolic-to-diastolic ratio and the resistance in dex were determined at each examination. Compliance with the medical r egimen was assessed by pill counts and measurement of maternal serum t hromboxane B2 levels. RESULTS: The prerandomization Doppler index valu es were similar between the two randomization groups in the 538 (aspir in 266, placebo 272) patients studied. We found no significant differe nces with univariate comparisons and multiple linear regression modeli ng in the postrandomization Doppler index values (p = 0.21 to 0.96). N o differences were found when patients were assessed by randomization assignment group (intent to treat) or by biochemical evidence for comp liance and absence of crossover with maternal serum thromboxane B2 lev els. CONCLUSION: The use of low-dose aspirin from 24 weeks' gestation until delivery does not significantly affect umbilical artery Doppler index values.