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):
- Standardized Pediatric Blood Pressure Chart - Boys
- Standardized Pediatric Blood Pressure Chart - Girls
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
- A 10-year-old boy in the 90th height percentile
- A 5-year-old girl who is 116cm tall
Answers to Example Questions:
10-year-old boy in 90th height percentile:
- 90th Percentile Blood Pressure = 118/77
- 95th percentile blood pressure = 122/81
- Height Percentile = 95th
- 90th Percentile Blood Pressure = 109/69
- 95th percentile blood pressure = 113/73