About 1 in 10 women have high blood pressure (hypertension) during pregnancy. You may have had high blood pressure in the past or it may have been diagnosed for the first time during pregnancy.
Planning a pregnancy when you have a history of high blood pressure
If you have a history of high blood pressure, your GP or specialist can help you plan your pregnancy.
Talking to them before you get pregnant gives you the chance to change to a different blood pressure medicine if the one you’re taking isn’t safe for pregnancy.
If you’re already pregnant, speak to your doctor straight away so they can make sure your blood pressure medication is safe to continue taking.
Your doctor will also give you information about how a healthy diet and active lifestyle can help to lower your blood pressure. For example, cutting down on the amount of salt in your food and doing some exercise, such as brisk walking or swimming, every day can also help.
During your pregnancy, your midwife and doctor will monitor your blood pressure to make sure it doesn’t harm you or your baby.
High blood pressure before pregnancy means you are at higher risk for a pregnancy condition called pre-eclampsia (see below).
What happens if I develop high blood pressure during pregnancy?
If you develop high blood pressure during pregnancy, your doctor or midwife will check it once or twice a week until it falls to 135/85 mmHg. They may also offer you medication to lower your blood pressure.
What if I develop severe high blood pressure during pregnancy?
If you have severe high blood pressure (160/110 mmHg or higher) you may need to go into hospital, where health professionals will monitor you and your baby. They will give you medication to lower your blood pressure.
If your blood pressure stays high and you are more than 37 weeks pregnant, your doctor or midwife will talk to you about whether it would be safer to deliver your baby early. They will explain the advantages and disadvantages of this so you can decide what is best for you and your baby.
Can high blood pressure harm me and my baby?
If high blood pressure isn’t treated, there’s a higher chance of you having a stroke, where the brain can’t get enough oxygen and nutrients. Your baby is more likely to be smaller than usual at birth or need to stay in neonatal intensive care.
High blood pressure together with protein in the urine after 20 weeks of pregnancy can be a sign of pre-eclampsia. Most cases of pre-eclampsia are mild but if severe pre-eclampsia is left untreated, it can be dangerous for the mother and baby.
Be aware of the following symptoms and contact your doctor or midwife straight away if they happen to you:
- a very bad headache
- sight problems, such as blurring or flashing lights
- severe pain just below your ribs
- sudden swelling in your face, hands or feet.
After the birth
Your midwife will check your blood pressure regularly for a few days after you’ve had your baby. If you take medication, you may need to carry on taking this until your blood pressure returns to a safe level. Before you leave hospital, your midwife will tell you how your blood pressure will be checked at home.