Preeclampsia is a multisystem disorder that complicates 6% to 8% of pregnancies, with higher rates in women with preexisting hypertension, diabetes mellitus, or previous history of preeclampsia. Recent large randomized trials, including two large trials conducted by members of the Maternal-Fetal Medicine Network, have not shown a benefit in reducing the rate of preeclampsia or perinatal outcome from the use of low-dose aspirin. Secondary analysis from these trials revealed that the onset of mild gestational hypertension or mild preeclampsia at or near term was associated with minimal to low neonatal and maternal morbidities. During review of the medical records we found considerable differences among the various centers regarding the definitions of both mild and severe preeclampsia. These differences were more prevalent in those women with pre-existing hypertension or diabetes mellitus. The majority of adverse pregnancy outcomes occurred in women who developed severe gestational hypertension-preeclampsia prior to 35 weeks' gestation and in those women with previous preeclampsia and/or pre-existing vascular disease. We also found that epidural anesthesia is safe in parturients receiving low-dose aspirin in pregnancy and in women with severe preeclampsia. © 2003 Elsevier Inc. All rights reserved.