Retrospective comparison of blood pressure course during preeclamptic and matched control pregnancies.

A decrease in systemic blood pressure by midtrimester of normal pregnancy has been observed by many investigators. To examine the timing of onset of this decline and to study early behavior of blood pressure in pregnancies complicated by preeclampsia, we reviewed the outpatient charts of all patients with preeclampsia who received prenatal care at our clinics during the past 3 years. The 30 patients who met our criteria for preeclampsia were matched for age, race, and parity with normotensive control subjects. We found that in normal pregnancies, decline in blood pressure occurred before the second trimester and blood pressure remained low throughout gestation, rising insignificantly near term. Both systolic and diastolic blood pressures were significantly higher (p less than 0.05) for patients with preeclampsia than for normal control subjects beginning in the first trimester. This difference persisted throughout pregnancy and was also present at the 6-week postpartum visit (p less than 0.025).