Comparisons of mercury-free and automated sphygmomanometers with mercury sphygmomanometry in hypertensive and normotensive pregnant women: parallel, prospective, observational study

Blood pressure was measured in hypertensive and normotensive pregnant women comparing an automated blood pressure measuring device and a mercury-free sphygmomanometer with a mercury sphygmomanometer as the gold standard. Both of the test devices use a standard blood pressure cuff, but have different ways of determining the blood pressure. The automated device inflates and measures blood pressure electronically, while the non-mercury device uses a manual bulb to inflate and deflate the cuff, similar to mercury sphygmomanometry. Pregnant women were allocated on a non-random basis to either having the automated device vs mercury or the mercury-free device vs mercury. Each women then had nine blood pressures taken, alternating between mercury and the test device over a 20 minute period.