Blood pressure is the force of blood against the arterial vessels during contraction of the heart. Blood pressure varies throughout the day, depending on activities. Blood pressure also varies between infants, children and adults. It is important to know normal blood pressure values in order to prevent complications and to live healthier lives.
Preemies and Extreme Preemies
Normal blood pressure for premature babies is based on gestational age and weight. The mean arterial pressure (map) which is MAP = [(2 x diastolic) + systolic] divided by 3, should not be less than the child's gestational age. For example [(2 x 28) + 49)]/3=35. So, a 35-week preemie should have a blood pressure of about 49/28 (35) as a neonate. This is not written in stone. Other conditions affecting preemies and extreme preemies, who are usually sick and hospitalized at birth, should be considered. The best way to evaluate blood pressure is to evaluate heart rate, pulses, color, urine output, activity and temperature rather than looking at the blood pressure alone.
Children Less Than 1 Year
Normal blood pressure in children less than 1 year is usually 70/30 or greater. It can be higher or lower, depending on activity and circumstances.
Toddlers, Children, Adolescents
When calculating a child's (greater than 1 year) normal blood pressure consider this formula: 90 + 2(age in years) is normal; 70 + 2(age in years) is the lower end. For example: A 7-year-old child's systolic (top number) pressure would be between 70 + 2(7) =84 and 90 + 2(7) =104. The bottom number (diastolic) should be 30-45 less than the systolic number. So the healthy 7-year-old child's pressure should be from 84/39 to 104/59.
According to the National Heart, Lung and Blood Institute (See the link in references), normal blood pressure in adults is less than 120/80. 120-139/80-89 is indicative of pre-hypertension; 140-159/90-99 is Stage I hypertension; greater than 160/100 is Stage II hypertension.
Remember to look at the whole picture. A person with good pulses, good heart rate, good urine output, healthy-looking, warm and dry, and in no distress, may tolerate a lower blood pressure than the guide indicates. Also, remember that elevated blood pressure can cause life-threatening complications in adults and children.