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Blood Pressure

The force exerted by the blood upon the walls of the blood vessels.

Blood pressure is recorded as two numbers.
  • The top number is called the systolic blood pressure. This is the pressure in the blood vessels when the heart contracts
  • The bottom number is called the diastolic blood pressure. This is the pressure in the blood vessels when the heart is relaxed.
  • The pressure above would be read as 120 over 80 . Blood pressure is measured in millimeters of mercury (mm Hg)

    Classification of Blood Pressure Levels in Adults

    Category Systolic    Diastolic
    Normal Less than 120 AND Less than 80
    Prehypertension 20 to 139 OR 80 to 89
    High Blood Pressure (Hypertension)
    Stage 1 140 to 159 OR 90 to 99
    Stage 2 160 or higher OR 100 or higher

    The elevated blood pressure readings should be documented on at least two occasions at least four hours apart. 


    1. National High Blood Pressure Education Program.The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure.
    Bethesda (MD): National Heart, Lung, and Blood Institute (US); 2004 Aug.PMID: 20821851
    2.Pickering TG, et. al., Recommendations for blood pressure measurement in humans and experimental animals: part 1: blood pressure measurement in humans: a statement for professionals from the Subcommittee of Professional and Public Education of the American Heart Association Council on High Blood Pressure Research.
    Circulation. 2005 Feb 8;111(5):697-716. PMID: 15699287

    3. Hypertension in pregnancy: executive summary. Obstet Gynecol. 2013 Nov;122(5):1122-31. doi:10.1097/01.AOG.0000437382.03963.88.PMID:24150027



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