To the Editor.
—"A Meta-analysis of Low-Dose Aspirin for Prevention of Pregnancy-Induced Hypertensive Disease," by Imperiale and Petrulis,1 and "A Multivariate Analysis of Risk Factors for Preeclampsia," by Eskenazi et al,2 add to the growing knowledge3,4 of the potential to improve pregnancy outcome with daily low-dose aspirin starting in the second trimester. The meta-analysis combines studies for preventing pregnancy-induced hypertension with those for preventing recurrent fetal growth retardation. An additional recent study by Uzan et al5 provides more extensive data supporting prevention of fetal growth retardation with aspirin. Thus, thromboxane-induced placental insufficiency does not appear to be limited to pregnancies with hypertension.The published data suggest that pregnancy risk groups to be considered for low-dose aspirin include (1) primiparae, especially those who are black, and (2) women with (a) previous pre-eclampsia, (b) a history of previous fetal growth retardation not explained by other causes, and (c