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What Do My Child’s Blood Pressure Readings Mean?

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Updated October 04, 2007

Interpreting blood pressure readings for children is somewhat complicated compared to adults. While adult blood pressure readings can easily be compared to simple published values for what is considered to be normal and abnormal, such easy comparisons aren’t possible for children. Because children’s bodies change so quickly early in life, blood pressure readings must be adjusted for height, age, weight, and gender.

These adjusted readings are then compared to complicated tables that list “percentile ranges.” A percentile range tells the doctor how the measured blood pressure compares to other children by looking at the combined blood pressure readings from millions of individual children.

For example, if your doctor tells you that your child’s blood pressure is in the 65th percentile, that means 35% of children of the same age, height, weight, and gender have higher blood pressure than your child. For most purposes, blood pressures from about the 50th to 90th percentiles are considered to be within the range of normal, while higher or lower values may indicate the need for medical intervention.

How to Interpret Pediatric Blood Pressure Readings

The Centers for Disease Control (CDC) maintain the data used to produce the official blood pressure percentile charts, and all of the data is freely available to the public. The individual measurements of height, weight, and body mass index (BMI) used to produce the percentile charts are also available for download (PDF Format):

This raw data, gathered from a large series of scientific and clinical projects collectively known as the National Health and Nutrition Examination Survey (NHANES), will let you see how your child’s physical statistics compare to national averages for the United States. More useful, though, are the standardized blood pressure percentile charts that have been compiled using the raw NHANES data. The compiled blood pressure percentile charts are available for download via the links below:
To use the standard charts, first make sure that you choose the proper male or female chart. Scan the left-most vertical column to find the row that matches your child’s age. Notice that each age has individual rows for the 90th and 95th percentile blood pressure. The vertical columns each represent a height percentile. Matching a height column with the 90th or 95th percentile age-specific blood pressure row shows you the numerical value for that blood pressure percentile.

This process sounds more complicated than it actually is. Let’s try an example. Say that you have a 4-year-old boy who is 103cm tall (40.5 inches, or about 3.5ft). You first look at the CDC height by age chart to find your child’s height percentile. A 4-year-old boy who is 103cm tall would be in approximately the 75th height percentile (find the point where the age and height intersect, and choose the nearest curve). Now, using the blood pressure percentile chart, you can find the cutoff values for the 90th and 95th percentile blood pressures in a 4-year-old boy who is in the 75th height percentile. Using the blood pressure chart yields these values for our example child:

  • 90th percentile blood pressure = 109/65
  • 95th percentile blood pressure = 113/69
Try working out the 90th and 95th percentile blood pressures for these examples (answers at the end of this article):
  • A 10-year-old boy in the 90th height percentile
  • A 5-year-old girl who is 116cm tall
After working with these charts, you see that matching up all of the necessary data can be complicated. While the process isn’t very difficult, it can be confusing and time consuming. For these reasons, it is best to leave the job of figuring out the official interpretation of your child’s blood pressure to a trained healthcare professional.

Answers to Example Questions:

10-year-old boy in 90th height percentile:

  • 90th Percentile Blood Pressure = 118/77
  • 95th percentile blood pressure = 122/81
5-year-old girl who is 116cm tall:
  • Height Percentile = 95th
  • 90th Percentile Blood Pressure = 109/69
  • 95th percentile blood pressure = 113/73

Sources

  1. Third National Health and Nutrition Examination Survey, 1988-1994.
    http://www.cdc.gov/nchs/products/elec_prods/subject/nhanes3.htm
  2. Lurbe, E, Sorof, JM, Daniels, SR. Clinical and research aspects of ambulatory blood pressure monitoring in children. J Pediatr 2004; 144:7.
  3. Dasgupta, K, O'Loughlin, J, Chen, S, et al. Emergence of sex differences in prevalence of high systolic blood pressure: analysis of a longitudinal adolescent cohort. Circulation 2006; 114:2663.
  4. Rosner, B, Prineas, RJ, Loggie, JM, Daniels, SR. Blood pressure nomograms for children and adolescents, by height, sex, and age, in the United States. J Pediatr 1993; 123:871.
  5. DHHS, PHS, NIH, National Heart, Lung, and Blood Institute. Update on the Task Force Report (1987) on High Blood Pressure in Children and Adolescents: A Working Group Report from the National High Blood Pressure Education Program. NIH Publication 96-3790; 1996; 7-9.

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