What is blood pressure?

Your blood pressure is a measure of how strongly your blood pushes against the walls of your blood vessels.

It's normally recorded in 2 numbers:

• The top number (systolic) is the pressure when the heart is pumping.
• The bottom number (diastolic) is the pressure in between each heartbeat.

During your pregnancy, your blood pressure will be checked at each antenatal visit. When you are pregnant, your blood pressure is considered high if the top number is 140 or more, or if the bottom number is 90 or more (described as '140 over 90').

High blood pressure (also known as 'hypertension') in pregnancy is a common medical problem that usually gets better after the birth of your baby. In some cases, it can be a sign of a serious condition that can happen during pregnancy called pre-eclampsia.

If your blood pressure is high, your doctor will create a plan for treatment and monitoring during your pregnancy.

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Different types of high blood pressure in pregnancy

There are 3 types of high blood pressure during pregnancy:

• Chronic hypertension — This is when you already had high blood pressure before you got pregnant. Chronic hypertension increases your risk of getting pre-eclampsia during pregnancy. Hypertension is also called ‘chronic' when diagnosed in the first 20 weeks of pregnancy.
• Pregnancy-induced hypertension (gestational hypertension) — This is high blood pressure diagnosed after at least 20 weeks of pregnancy.
• Pre-eclampsia — Pre-eclampsia is a serious complication of pregnancy. It causes high blood pressure and can affect one or more of your organs including your liver, kidneys, blood and brain.

Symptoms of pre-eclampsia include:

• a bad headache that doesn't get better with painkillers
• blurry vision or flashes of lights
• feeling sick (nausea)
• sudden swelling of your hand or feet
• pain in your upper abdomen (tummy) or ribs

If you or someone you know is pregnant and has any of these symptoms, it's important to seek urgent medical care at your nearest hospital.

​What are the risk factors for high blood pressure during pregnancy?

Anyone can develop high blood pressure during pregnancy, but you are at increased risk if you:

• have had pre-eclampsia before
• have close relatives that had pre-eclampsia
• have a medical condition such as kidney disease, diabetes or chronic hypertension
• are older than 40 years of age
• are living with overweight or obesity
• are pregnant with more than one baby
• conceived with in vitro fertilisation (IVF)

Can high blood pressure affect my baby?

High blood pressure in pregnancy can stop enough blood from flowing to the placenta. This might mean that your baby doesn't get enough nutrients or oxygen.

Untreated high blood pressure can increase your baby's risk of complications such as:

• low birth weight
• preterm labour and/or premature birth
• placental abruption
• stillbirth

To reduce the chance of complications, it's important that high blood pressure is noticed and treated early.

​How does high blood pressure in pregnancy affect me?

High blood pressure in pregnancy increases your risk of developing pre-eclampsia and its associated complications.

If you have high blood pressure in pregnancy you will be offered additional check-ups for you and your baby. This can include extra tests:

• More frequent blood pressure readings
• Blood and urine (pee) tests
• Ultrasounds to check your baby, placenta and the fluid around your baby
• Cardiotocography (CTG) to check your baby's heart rate

It's important that you attend all your appointments. Ask your midwife or doctor if you have any questions about your care.

If you have signs of pre-eclampsia you might be treated by a team of health care professionals, such as:

• an obstetrician
• a midwife
• an obstetric physician
• an anaesthetist
• a neonatologist (specialist in care of newborns) or paediatrician

If you experience high blood pressure in pregnancy, you are more likely to develop high blood pressure or heart disease in later life.

How is high blood pressure in pregnancy treated?

Your midwife or doctor will check your blood pressure regularly. If you have high blood pressure, you can help manage it by:

• quitting smoking and vaping
• eating a healthy diet
• exercising regularly
• maintaining a healthy weight

If you took medicines to control your blood pressure before your pregnancy, talk to your doctor about what medicines are safe to take during pregnancy.

You doctor can prescribe medicines to lower your chance of getting pre-eclampsia. Ask your doctor if there are medicines that may be helpful for your situation.

Both you and your baby will also need to be closely monitored as pre-eclampsia can quickly get worse. If this happens, you may need to be monitored in hospital. You may need to give birth to your baby early.

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How does high blood pressure impact labour and birth?

During labour, your baby's heart rate may be continuously monitored. Your midwife or doctor may recommend an intravenous drip to give you fluid and medicines.

If your condition seems to be worsening during labour, your doctor may suggest an emergency caesarean to birth your baby quickly.

If you have pre-eclampsia, it's usually best to plan to give birth in a large maternity hospital. This is so you and your baby can get expert care if you need it. This is important if your baby ends up being premature or smaller than expected.

​​​​​​​Will my blood pressure stay high after the birth?

Hypertension that starts during pregnancy usually goes away after the baby is born. However, there may still be some complications during the first few days after the birth. You should have extra blood pressure monitoring for several weeks.

If you had pre-existing chronic hypertension, see your doctor to check about your ongoing treatment.

​Are there any implications for future pregnancies?

Having high blood pressure during your pregnancy doesn't always mean you will get hypertension again in future pregnancies. However, your risk is increased, especially if you have a medical condition such as obesity, kidney disease or diabetes.

​Resources and support

Speak to your midwife or doctor if you have questions about hypertension during pregnancy.

The Royal Women's Hospital has information on high blood pressure and preeclampsia.

The Royal Australian and New Zealand College of Obstetricians and Gynaecologists has a factsheet on high blood pressure and preeclampsia during pregnancy.

​​​​​​​Languages other than English

The Society of Obstetric Medicine of Australia and New Zealand has multilingual resources about pre-eclampsia and other pregnancy topics.