Maternal serum thromboxane B2 reduction versus pregnancy outcome in a low-dose aspirin trial

Objective: Our purpose was to determine whether in a low-dose aspirin trial a longitudinal decrease in maternal serum thromboxane B2 is associated with improvement in pregnancy outcomes. Study Design: a total of 606 healthy nulliparous women with singleton gestations were randomized at 24 weeks to either 60 mg of aspirin or a placebo. Maternal serum thromboxane B2 was measured at randomization, at 29 to 31 weeks, at 34 to 36 weeks, and at delivery. After delivery, and without knowledge of patient outcome or group assignment, patients were categorized as having had either a longitudinal twofold or greater (≥50%) or less than twofold reduction (