Diversity of blood pressure recording during pregnancy: implications for the hypertensive disorders

To determine the number and type of methods used to measure blood pressure (BP) in pregnant women.

Questionnaires were distributed to obstetricians and midwives concerning: method of recording BP (arm used, subject position, Korotkoff sounds recorded); accuracy of recording BP (cuff size, sphygmomanometer calibration); and definitions of hypertension in pregnancy.

Obstetricians (academic, staff and private) in Sydney; members of the New South Wales Midwives' Association.

Responses were received from 85 obstetricians (55% of those surveyed) and 173 midwives (43%); the overall response rate was 46%. Almost 80% of respondents agreed that diastolic BP above 90 mmHg constituted hypertension during pregnancy but at least six different methods were used to obtain BP readings, with a potentially large variability in the BP so obtained. Forty-five per cent of obstetricians and 72% of midwives stated that they always used a large cuff when necessary. Few had had their sphygmomanometer calibrated within the previous two years.

There is considerable variability in the way BP is recorded in pregnant women. Hypertension in pregnancy may therefore be over or under diagnosed according to the method employed and there is an urgent need for international consensus on how to measure BP accurately in pregnancy.