High blood pressure in pregnancy - what to look out for

Making sure your blood pressure is at a normal level is an important part of antenatal care and it will be checked at all your appointments

Dr Sophie Kefi from Doctor Care Anywhere has all the information you need on symptoms, prevention and treatment during pregnancy.

blood pressure test

What is high blood pressure?

Also known as hypertension, in simple terms it means that the pressure of blood in your arteries is too high. 

A blood pressure reading of millimetres of mercury (mm/Hg) shows two numbers: the systolic (the pressure in the arteries when the heart contracts) over the diastolic (the pressure in the arteries when the heart is resting).

High blood pressure is considered to be a reading of 140/90 or higher. This would be classed as 'mild' hypertension. A reading of 150/100 or more is 'moderate' hypertension and anything over 160/110 is termed 'severe'.

How common is it to have high blood pressure during pregnancy?

You may well have had high blood pressure before you got pregnant. If it's found before 20 weeks, it's considered to be pre-existing (known as 'chronic hypertension') and will probably still be high after you give birth. If you were already on drugs for your blood pressure, your GP may look at altering them during the pregnancy.

High blood pressure diagnosed after 20 weeks is 'gestational hypertension'. This is brought on by pregnancy and usually returns to normal within six weeks of giving birth. Around 16% of women will have pregnancy-induced hypertension.

What are the signs of high blood pressure?

There are usually few signs of high blood pressure, which is why it will be checked at all your antenatal appointments.

There are, however, some symptoms you should look out for, as they can be signs of pre-eclampsia (see below). 

Can high blood pressure be treated during pregnancy?

The way that high blood pressure is treated will depend on how severe it is, and what stage you are at in your pregnancy. Once it's discovered, it's likely that you will be more closely monitored for the remainder of your pregnancy with frequent blood pressure and urine checks. In some cases, you may be given drugs to reduce it.

What can I do to lower my blood pressure in pregnancy?

Hypertension definitely falls into the 'prevention is better than cure' camp. Maintaining a healthy weight, getting plenty of exercise and keeping a diet low in salt and high in fresh fruit and veg can all help to keep blood pressure normal. Relaxing as much as you can is also a good idea.

doctor blood pressure check 

Is high blood pressure in pregnancy dangerous for me or my baby?

It can be serious (see pre-eclampsia, below), but it is rare. As long as it is picked up and monitored you shouldn't need to worry - and worrying is also no good for your blood pressure! Most mild to moderate cases will cause no real problems. 

However, the earlier in pregnancy you develop high blood pressure, and the higher your reading, the greater the chances are of encountering problems. 

Will high blood pressure affect my labour or birth?

Unless it's severe, it shouldn't. You may be monitored more closely during labour. Medical staff will also keep a careful eye on you in later pregnancy and, if you have severe hypertension, you may be advised to have a planned Caesarean or assisted delivery rather than an unassisted vaginal birth when the time comes. If the high blood pressure develops to become pre-eclampsia, you could be induced early. 

High blood pressure and pre-eclampsia

Pre-eclampsia is a condition that can affect women in the second half of their pregnancy (usually post 27 weeks) and just after birth. High blood pressure is often one of the first signs of it developing.

It's not known exactly what causes it but it seems to be connected to problems with the placenta. The condition reduces the flow of blood through the placenta and can make both mother and baby quite ill, causing damage to your liver and kidneys. 

If there are complications, it can develop into eclampsia, which causes fits in the mother. Very rarely, it can cause potentially fatal complications, for mother or baby.

Early symptoms include high blood pressure and traces of protein in your urine. Other symptoms include: 

  • severe headaches
  • dizziness
  • visual disturbance
  • vomiting
  • sudden fluid retention
  • puffiness in the face, hands and feet
  • upper abdominal pain
  • just feeling 'not right'
  • reduced foetal movement 

If pre-eclampsia is diagnosed, your midwives and doctors will try to prevent it developing into full-blown eclampsia. You may be required to monitor your blood pressure and baby's movements at home, and you might be put on bed rest,. Some women are given treatment during labour or advised to have an assisted delivery. If it is severe, you could be advised to have your baby pre-term.

What Mumsnetters say about high blood pressure in pregnancy

"I have had high blood pressure in all three pregnancies (the first was the worst - I was given medication). Each time they kept an eye out, did extra checks etc to constantly rule out pre-eclampsia. It shot up very high during the labours, which was a pain as I then couldn't have water births, use midwife-led units etc and had to have different medication. But the babies were always fine and my blood pressure always returned to normal straight after the birth."

"I've been admitted to hospital twice with high blood pressure - last time it was 210/115 at my GPs. His expression was priceless - he sent me straight in. I'm on Labetalol daily and it's back down to high, which is normal for me. I'm checking it myself every day and seeing a doctor every fortnight. The scary thing is that when it was really high, I felt fine, so I wouldn't know if if happened again."

"I know it's scary, but remember if they're aware that high blood pressure is an issue they will make sure you get the right treatment - and not all high blood pressure develops into pre-eclampsia, my childminder developed high blood pressure midway through her pregnancy and was put on medication for it and went on to have a healthy baby girl at term."

Liked this? Try these:


Preventing varicose veins in pregnancy Heartburn and indigestion during pregnancy Advice on flying while pregnant

Last updated: 4 months ago