Automated self-initiated blood pressure or 24-hour ambulatory blood pressure monitoring in pregnancy?

Objective To determine whether self-initiated and recorded automated blood pressure measurement can provide an accurate estimate of ambulatory blood pressure in pregnant women suspected of having 'white coat hypertension'. Design A prospective observational study. Setting Women's and Children's Health Unit, St George Hospital, a teaching hospital of the University of New South Wales. Population Pregnant women being assessed for possible 'white-coat hypertension'. Methods Sixty-six pregnant women who were undergoing 24 hour ambulatory blood pressure monitoring (ABPM) in their home or work environment also measured their blood pressure six times during this interval using a self-initiated automated blood pressure recorder (Omron HEM 705CP). Agreement between awake ABPM and Omron recorded blood pressures was tested by Bland-Altman analysis. Main outcome measure Limits of agreement between blood pressures measured by each device. Results Average blood pressures obtained by the two devices were identical (125/77 mmHg) but limits of agreement were wide, -20 to +23 mmHg for systolic blood pressure and -9 to +15 mmHg for diastolic blood pressure. Conclusion The Omron HEM 705CP is a useful device for measuring group average blood pressures in pregnant women suspected of having white coat hypertension but cannot reliably replace ABPM for clinical management of individual pregnant women.