Figure 1. Flow diagram of patient population.
a Four sets of twins were included in the study; 3 sets only had 1 twin eligible at the start of the study. One set initially had both twins eligible, however 1 infant required a blood transfusion secondary to extreme anemia and became a screen failure. b Aged out indicated those mothers who stayed pregnant past 32 weeks 0 days gestation and therefore were no longer eligible for the study. AEDF/REDF, Absent end-diastolic flow/ reverse end-diastolic flow.