What is blood pressure?

Blood pressure is a measure of the force with which the heart pumps the blood around the body. Blood pressure is often shortened to BP.

As the heart beats, or contracts, it pushes blood through tubes called arteries.

When the heart relaxes between beats, blood returns to the heart through blood vessels called veins.

The kidneys help control blood pressure to keep it at a healthy level. One of the ways they do this is by regulating how much salt and water is in the body. If the kidneys are not working properly, they may not be able to control blood pressure very well.

It is very important that your child’s blood pressure is in a healthy range.

High blood pressure

Hypertension is when the blood pressure is too high. This can be serious, especially if it remains high for a long time. Hypertension can increase the risk of getting heart disease, chronic kidney disease (CKD) or having a stroke.

Some children with hypertension have no symptoms, but some may experience:

  • headaches that do not go away
  • vomiting (being sick)
  • blurred (fuzzy) vision.

Hypertension in children is rare but increasing. It is more common in children who are severely overweight or have kidney disease. If your child has high blood pressure, your doctor will try to find out what is causing it and whether it is affecting other parts of their body, such as the kidneys. Your child may need to make changes to their diet and/or take medicines.

Low blood pressure

Hypotension is blood pressure that is too low. This can happen when an illness comes on suddenly (acute disease) or as a side-effect of some medicines. Some children with hypotension may have no symptoms, but some may experience:

  • dizziness or light-headedness
  • fainting
  • general weakness

Why does my child need their blood pressure measured?

Children may have their blood pressure measured for many reasons, including:

  • during a routine doctor’s appointment
  • as part of routine monitoring for existing heart or kidney disease
  • when they are admitted to hospital
  • before an operation

Blood pressure measurements

A blood pressure measurement has two numbers.

The top number is called the systolic pressure – the pressure when the heart beats.

The bottom number is called the diastolic pressure – the pressure when the heart relaxes.

Blood pressure changes from day to day and at different times of the day. It can also change when we feel stress and during exercise.

More information

  • Hypertension

    Hypertension (blood pressure that is too high) is rare in children, and may be a serious condition. Your child's doctor will try to find out what is causing it.

  • Meet a Paediatric Nurse

    Denise and Rachel are both paediatric nurses at the Great North Children’s Hospital in Newcastle and their roles centre around the practical and emotional elements of kidney disease treatments.

  • Blood pressure and your child’s health

    Understand more about children's blood pressure, how the kidneys control blood pressure to help make sure it is at a healthy level and how you can keep the whole family's blood pressure in a healthy range.