Predicting the development of pregnancy-associated hypertension. The place of standardised blood-pressure measurement.

82 initially normotensive pregnant women with no known history of renal disease were seen at monthly intervals from 16 weeks' amenorrhoea onwards, and their blood-pressure (B.P.) was measured sitting and lying on their left side. 15 developed hypertension (B.P. greater than 135/85 mm Hg lying on the left side) in late pregnancy. When these women were compared with the 67 who remained normotensive throughout, their B.P.s were found to be significantly higher even in early pregnancy, although individual patients were not always separable in this way. When B.P. measured in this rigidly standardised manner was compared with routine antenatal clinic values, it was apparent that the latter did not detect the difference between the two groups. Women who develop hypertension in the third trimester of pregnancy (pre-eclampsia) may represent a separate group from entirely normal pregnant women from the beginning of pregnancy.