High Blood Pressure in Pregnancy

What does it mean, and when does it become a concern?

Having your blood pressure checked is a routine part of pregnancy care. Most of the time, it's simply one of those things your midwife does at your appointments while you get on with thinking about considerably more exciting things. But sometimes your blood pressure is higher than expected. This can happen for several different reasons, and having a high blood pressure reading does not automatically mean you have pre-eclampsia. It does mean your maternity team will want to keep a closer eye on you and your baby.

What is High Blood Pressure?

Blood pressure is recorded as two numbers, for example 120/80 mmHg. The first number is your systolic blood pressure, which is the pressure when your heart contracts. The second is your diastolic blood pressure, which is the pressure when your heart relaxes.

In pregnancy, hypertension is generally defined as a blood pressure of 140/90 mmHg or higher. A reading of 160/110 mmHg or higher is considered severe hypertension and needs urgent treatment. One high reading doesn't necessarily tell the whole story. Your healthcare team will consider your blood pressure alongside your symptoms, urine tests, blood tests and your baby's wellbeing.

Why do they check my blood pressure so often?

High blood pressure often doesn't make you feel unwell. That's why your blood pressure is checked regularly during antenatal appointments, alongside urine testing. These checks can help identify hypertension and signs of pre-eclampsia, sometimes before you notice anything yourself. So if you're feeling absolutely fine but your midwife says your blood pressure is higher than expected, that doesn't mean the reading is unimportant. And equally, feeling fine doesn't mean you should ignore symptoms if they develop later.

Different types of hypertension in pregnancy

You may hear several different terms.

Chronic hypertension

This means you had high blood pressure before pregnancy or before 20 weeks of pregnancy. If you have chronic hypertension, your maternity team will usually arrange additional monitoring and discuss how best to manage your blood pressure during pregnancy.

Gestational hypertension

This means you develop high blood pressure after 20 weeks of pregnancy, without the additional features that would lead to a diagnosis of pre-eclampsia. You may need more frequent blood pressure checks and monitoring of your baby. Some people with gestational hypertension will need medication. Others may simply need closer monitoring, depending on their blood pressure and individual circumstances.

Pre-eclampsia

Pre-eclampsia is a more complex pregnancy condition involving high blood pressure and signs that other parts of the body, or the placenta, may be affected. It usually develops after 20 weeks of pregnancy, although it can occasionally happen earlier or after your baby has been born. We'll look at pre-eclampsia in more detail below.

What is Pre-eclampsia?

Pre-eclampsia is a condition associated with pregnancy that can affect your blood pressure and organs such as your kidneys, liver and brain. It can also affect how well the placenta is functioning and therefore how your baby grows. One of the things your maternity team looks for is protein in your urine, but pre-eclampsia isn't simply "high blood pressure plus protein in your urine". Other signs of organ or placental dysfunction can also be involved. This is why your maternity team may carry out several different checks if your blood pressure becomes elevated.

What are the Symptoms of Pre-eclampsia?

You may have no symptoms at all, which is why routine antenatal checks matter. However, symptoms that need urgent assessment include:

a severe headache that doesn't go away
problems with your vision, such as blurred vision or flashing lights
severe pain just below your ribs
sudden swelling of your face, hands or feet
feeling very unwell
nausea or vomiting
heartburn that doesn't go away with medication

These symptoms can have other causes too, but they need checking during pregnancy. If you're pregnant and develop symptoms that could indicate pre-eclampsia, contact your maternity unit urgently. If you've recently given birth and develop these symptoms, you should also seek urgent medical advice. Pre-eclampsia can sometimes develop or continue after birth.

What happens if my blood pressure is high?

If your blood pressure is raised, you may be asked to have further checks. These can include:

repeat blood pressure measurements
urine tests
blood tests to check your kidneys, liver and blood count
monitoring your baby's growth
an ultrasound scan
monitoring your baby's heart rate
a PLGF blood test in some circumstances

PLGF stands for placental growth factor. NICE recommends PLGF-based testing between 20 weeks and 36 weeks + 6 days for people with suspected pre-eclampsia, including some people with gestational hypertension, to help rule out pre-eclampsia. The exact tests and frequency of monitoring will depend on your individual circumstances.

Will I Need Medication?

Possibly. If your blood pressure remains above 140/90, NICE recommends offering medication for gestational hypertension. There are several medicines that can be used during pregnancy. NICE recommends considering labetalol, with nifedipine or methyldopa as alternatives when labetalol isn't suitable. The choice should take account of your circumstances, possible side effects and your preferences. If you already take medication for high blood pressure and become pregnant, don't stop it yourself. Some blood pressure medicines aren't suitable during pregnancy, so speak to your doctor promptly about whether your medication needs to change.

Does high blood pressure mean I need to rest?

Not necessarily. You might hear advice about bed rest or being told to take things very easy, but bed rest isn't recommended as a treatment for gestational hypertension. Your maternity team may give you individual advice about activity depending on your circumstances, but having high blood pressure doesn't automatically mean you need to spend the rest of your pregnancy on the sofa.

Does high blood pressure affect my baby?

Sometimes. High blood pressure and pre-eclampsia can affect how well the placenta works, which can affect your baby's growth.

This is why you may be offered additional ultrasound scans and other monitoring. Having high blood pressure doesn't mean that your baby will definitely have a problem. The extra monitoring is there so that your maternity team can identify any concerns and respond if necessary.

Does high blood pressure mean I'll need an induction?

Not automatically. This is an important distinction because hearing "high blood pressure" can make people immediately assume that an early induction is inevitable. For people with gestational hypertension whose blood pressure remains below 160/110, NICE does not recommend planned early birth before 37 weeks unless there is another medical reason. After 37 weeks, the timing of birth should be agreed between the woman and her senior obstetrician, taking the individual circumstances into account.

If you have pre-eclampsia, the situation is different and the timing of birth will depend on how severe it is, how many weeks pregnant you are and how you and your baby are doing. Sometimes it is safer for a baby to be born early. Sometimes it is appropriate to continue the pregnancy with close monitoring. The important thing is that the recommendation should be based on your individual situation, rather than simply the label "high blood pressure".

What about Vaginal Birth?

High blood pressure doesn't automatically mean you cannot have a vaginal birth. If your blood pressure is within the target range, NHS guidance says it should not in itself prevent you from having a vaginal birth. Your blood pressure will usually be monitored during labour.

If you have severe hypertension or other complications, your maternity team may recommend additional monitoring or discuss assisted birth or caesarean birth. Again, the reason for the recommendation matters. If you're told that your blood pressure means your birth needs to happen in a particular way, it's reasonable to ask: "Can you explain why?"

What Happens after Birth?

Your blood pressure doesn't necessarily return to normal immediately after your baby is born. If you've had hypertension or pre-eclampsia, your blood pressure will continue to be monitored after birth. You may need to continue taking blood pressure medication for a while, and your treatment can be adjusted depending on your blood pressure. NHS guidance recommends follow-up after pregnancy for people who have had hypertension, including a blood pressure review at around 6 to 8 weeks after birth. Pre-eclampsia can also develop after birth, so don't assume that you're in the clear simply because your baby has arrived. If you develop symptoms such as a severe headache, vision problems, severe pain below your ribs, sudden swelling or feeling very unwell after birth, seek urgent medical advice.

Can I do anything to prevent high blood pressure?

There isn't a guaranteed way to prevent hypertension or pre-eclampsia. Your maternity team will assess your individual risk during pregnancy. If you're considered to be at higher risk of pre-eclampsia, you may be advised to take low-dose aspirin from 12 weeks of pregnancy. Some people may also be advised to take calcium supplements if they don't get enough calcium through their diet.

Don't start either of these yourself. Speak to your midwife or doctor about whether they are appropriate for you. Regular antenatal appointments are important because monitoring can identify changes that you may not notice yourself.

What Questions Can I Ask?

Being told that your blood pressure is high can make it difficult to take everything in. You might want to ask:

What was my blood pressure reading?
Is this gestational hypertension, chronic hypertension or something else?
Do I have any signs of pre-eclampsia?
Do I need any further tests?
What will you be monitoring?
How often will my blood pressure be checked?
Do I need medication?
What are the benefits and possible side effects?
Will I need additional scans?
How might this affect my birth options?
Are you recommending an induction? If so, why?
What are the benefits of giving birth then?
What are the risks of waiting?
What would happen if we continued the pregnancy with monitoring?
What symptoms should prompt me to contact maternity triage?
What monitoring will I need after my baby is born?

And if someone says, "We're recommending an induction because of your blood pressure," it's completely reasonable to ask them to explain what specifically about your blood pressure, your baby's wellbeing or your overall situation has led to that recommendation.

The Important Bits to Remember

High blood pressure in pregnancy is common enough that your blood pressure is checked routinely.
You may have high blood pressure without feeling unwell.
140/90 mmHg or higher is considered hypertension in pregnancy.
160/110 mmHg or higher is severe hypertension and needs urgent treatment.
Gestational hypertension and pre-eclampsia are not the same thing.
Pre-eclampsia can sometimes develop without obvious symptoms, which is why antenatal monitoring matters.
Severe headache, visual changes, severe pain below your ribs, sudden swelling or feeling very unwell need urgent assessment.
High blood pressure does not automatically mean you will need an induction or caesarean.
Additional monitoring is there to help your maternity team identify problems early.
Blood pressure problems can continue or develop after birth, so postnatal monitoring matters too.
You are allowed to ask why a particular treatment, test or recommendation is being suggested.

A high blood pressure reading is information. It isn't the whole story.

Explore Next

When to Seek Help
Know which symptoms in pregnancy need a call to your maternity team and which situations need urgent medical attention.

Pregnancy Appointments
Understand the checks that happen throughout pregnancy and why your blood pressure and urine are monitored.

Understanding Your Options
Explore common decisions and recommendations you may encounter during pregnancy and birth.

Induction of Labour
Understand why induction may be recommended, what it involves and the questions you can ask before deciding.

Preparing for Birth
Explore ways to prepare your body, mind and birth preferences whatever type of birth you're planning.