High Blood Pressure in Pregnancy

High Blood Pressure in Pregnancy

Raised blood pressure in pregnancy is fairly common, affecting about 10 – 15% of pregnancies. Some women might have high blood pressure before becoming pregnant whilst others may develop it during pregnancy, usually in the second half of pregnancy.

If your blood pressure is very high then it may pose some risks to your baby so it’s important to ensure that you attend antenatal appointments and take medication as prescribed.

There are three types of high blood pressure that can affect women during pregnancy: chronic high blood pressure (which may be pre-existing, or it could develop in the first 20 weeks of pregnancy), gestational (pregnancy induced) high blood pressure which develops after the 20th week of pregnancy and goes away within 6 weeks of the birth and pre-eclampsia, which also develops after 20 weeks and goes away within 6 weeks of the birth but has the additional feature of protein appearing in the urine and if untreated, may lead to fits or seizures in pregnant women.

Normal blood pressure is around 120/80 and it’s usual for your blood pressure to change during pregnancy, typically getting a bit lower throughout the first half and then going up again in the later half of pregnancy. Your midwife will check your blood pressure at your antenatal appointments. High blood pressure is divided into three categories and the severity of high blood pressure that you have will influence the treatment you are offered.

  • Mild hypertension (140/90 – 149/99) doesn’t usually need to be treated with medication but it needs to be checked regularly

  • Moderate hypertension (150/100 – 159/109)

  • Severe hypertension (160/110 or above)

Chronic high blood pressure

If you have chronic high blood pressure and you’re planning a pregnancy then you should check that it’s safe to continue any medication you take for your blood pressure. You might be advised to switch to a different medication if the medication you usually take isn’t recommended in pregnancy.

Your blood pressure will be measured regularly throughout your pregnancy and your medication will be adjusted if needed. You might have an extra growth scan to check that your raised blood pressure isn’t affecting your baby’s growth. Your blood pressure will be monitored during labour and after the birth.

Pregnancy induced high blood pressure

If your blood pressure increases over 140/90 in the second half of you pregnancy then you’ll be diagnosed with gestational hypertension. If it’s mild then you won’t need to take medication but if it becomes moderate or severe then you’ll be offered treatment with medication. Your urine will be tested regularly for protein and you may be offered some extra scans and monitoring.

Your blood pressure will be checked regularly during labour and after your baby is born. If you are prescribed medication for your blood pressure in pregnancy then you should be able to stop taking this within 6 weeks of your baby’s birth, as long as you blood pressure has decreased and your doctor says it’s safe to stop taking your medication.


If you develop high blood pressure during pregnancy and there is a significant amount of protein in your urine then you may have pre-eclampsia. This affects 2 – 5% of pregnancies and can be very serious.

Of course, you will only know if your blood pressure is raised or you have protein in your urine when these things are checked, but there are also symptoms of pre-eclampsia that you should be aware of. These include:

  • Severe headache

  • Problems with vision, such as blurring or flashing before the eyes

  • Severe pain just below the ribs

  • Vomiting

  • Sudden swelling of the face, hands or feet

If you experience any of these symptoms, particularly if your blood pressure has been raised in your pregnancy, then contact a healthcare professional urgently for advice.

Treatment will take into account the possible risks to you and your baby. You’ll need to go to hospital for assessment and you’ll probably be offered extra monitoring for you and your baby. In some cases it may be necessary to deliver your baby early and you might need to have your labour induced or have a caesarean section. If pre-eclampsia progresses then it can lead to seizures (fits) for the mother and in extreme cases the mother’s death.


If you’re taking medication for blood pressure and you want to breastfeed your baby you should discuss this with your doctor or midwife. Depending on the medication you’re taking this may well be possible but in some cases small amounts of some medications can be passed onto your baby in breast milk, which could affect your baby.