Blood pressure is the force of the blood pushing against the artery walls. Two numbers are recorded when measuring blood pressure:
Systolic pressure. This is the higher number. It refers to the highest pressure inside the artery. It occurs when the heart contracts and pumps blood to the body.
Diastolic pressure. This is the lower number. It refers to the lowest pressure inside the artery. It occurs when the heart relaxes and fills with blood.
For example, if a child's blood pressure is 110/70 mmHg, 110 is the systolic blood pressure and 70 is the diastolic blood pressure.
High blood pressure (hypertension) means that the pressure inside the arteries is too high. This higher pressure may harm the arteries and cause the heart to work harder.
- If the pressure is high when the heart contracts, then the systolic pressure will be high.
- If the pressure is high when the heart relaxes then the diastolic pressure will be high.
The systolic or diastolic pressure, or both, may be high.
Many things affect blood pressure. These include:
Time of day. Blood pressure changes throughout the day.
Physical activity. Blood pressure is usually higher during and right after exercise.
Emotions. Feeling angry, afraid, or happy can affect blood pressure. Feeling anxious or nervous at the healthcare provider's office may also affect blood pressure.
Age, height, weight, and gender. Blood pressure is lower in infants compared with older children. Taller children usually have higher blood pressure than shorter children. Overweight or obese children are more likely to have high blood pressure. And boys usually have slightly higher blood pressure than girls.
Illness or medicines. This might be heart disease or kidney disease.
Diet. Salt, foods with high salt content (such as packaged meats), alcohol, drinks with caffeine (such as coffee and soda) can all raise blood pressure.
One high blood pressure reading does not mean that your child has high blood pressure. Your child's healthcare provider will want to check your child's blood pressure over a period of days or weeks. When blood pressure stays high, it may be a problem.