A prospective study of blood pressure in pregnancy: prediction of preeclampsia.

A prospective study of blood pressure recording was conducted in 1000 patients, at each antenatal visit, with the use of an automatic random-zero sphygmomanometer. In 46 patients, among 808 primigravid women, who developed preeclampsia, the diastolic and mean blood pressures were significantly elevated compared to values at the first antenatal visit (p less than 0.01, 9 to 12 weeks). This difference was sustained throughout pregnancy until delivery by at least 10 mm Hg as compared to pressures in the normotensive group. Sensitivity for predicting preeclampsia early in pregnancy with an elevated blood pressure measurement (130 to 135/80 to 85 mm Hg) ranged from 16% to 57% while specificity ranged from 75% to 98%. The results substantiate an early vasospasm (9 to 12 weeks) in those women destined to develop preeclampsia.