High blood pressure in pregnancy (gestational hypertension)

What is gestational hypertension?

Gestational hypertension is high blood pressure that occurs after you’re 20 weeks pregnant.
If you had high blood pressure before 20 weeks, it’s likely that you had it before you even got pregnant. Your midwife will describe this kind of high blood pressure as essential chronic hypertension. This means that the high blood pressure was there before and you’ll continue to have it after you’ve given birth.

How will I know if I’ve got high blood pressure?

Your midwife will use a small monitor to take readings of your blood pressure. The readings will consist of two figures that look like a fraction, for example, 110/70.
The first, or top, number (110) records your blood pressure as your heart beats and pushes blood round your body. This is your systolic blood pressure.
The second, or bottom, number (70) is your blood pressure when your heart relaxes between beats. This is your diastolic blood pressure.
Once she has your numbers, your midwife will tell you if they are high. Your midwife will diagnose high blood pressure if:

• your blood pressure shows a reading of 140/90 or higher for two readings, four hours apart
• your blood pressure shows a one-off reading of the bottom number (diastolic) of 110 or more. The diastolic reading is more important in giving information about your health. So if this figure alone is high, it’s enough to mean you have high blood pressure.

If your midwife discovers you have high blood pressure during an antenatal appointment, she will ask you to have further tests at hospital. You may be at the hospital for several hours while your blood pressure is monitored hourly over three or four hours.

How common is high blood pressure in pregnancy?

High blood pressure is fairly common in pregnancy, affecting about one mum-to-be in 10.
Your blood pressure is more likely to rise if you were overweight at the start of your pregnancy.
Your midwife will work out your body mass index (BMI) at your booking appointment. A high BMI, of 30 or more, increases your chances of developing high blood pressure by up to four times. So your midwife will want to keep a close eye on you if you’re overweight.

Is high blood pressure in pregnancy serious?

Most cases of mild or moderate high blood pressure won’t cause any problems for you or your baby.
However, the earlier in pregnancy your blood pressure goes up, the greater your chance of developing pre-eclampsia later on.
High blood pressure is a sign of pre-eclampsia, a condition that influences how well the placenta works. If the placenta is not working as well as it should, it can affect how your baby grows. This is because your baby may not be able to get all the nutrients and oxygen she needs.
Your midwife will test your urine to see if it has protein in it. Having protein in your urine and high blood pressure are both signs of pre-eclampsia.
Your chances of developing pre-eclampsia are also higher if you are very overweight. Having close care from your midwife, especially if you are overweight, means she will pick up any signs of the condition.
The key thing with pre-eclampsia is to catch it early, so that you and your baby can be monitored and treated. You may have very high blood pressure and feel absolutely fine. That’s why it’s important to go to all your antenatal appointments so your midwife can check your blood pressure at each visit.
If your blood pressure is too high, you may be advised to see a hospital specialist. This will be the case whether your blood pressure rose after 20 weeks and you have gestational hypertension, or you had high blood pressure before you became pregnant.

How is high blood pressure in pregnancy treated?

Depending on how high your blood pressure is, you’ll be offered extra monitoring, blood tests, urine tests and, possibly, treatment. Blood pressure is only one factor in your health, so you may have scans too to check how your baby is growing.
If you had high blood pressure before you conceived (essential chronic hypertension), your doctor will prescribe medication to keep your blood pressure lower than 150/100.
If you were on medication before you became pregnant, this is likely to have been reviewed when planning your pregnancy or in early pregnancy. It’s also best to keep your salt intake low, as having a lot of salt can push up your blood pressure. Depending on your individual case, your midwife may organise extra antenatal checks for you.

Will my high blood pressure affect my baby’s birth?

It’s possible to have high blood pressure and have a straightforward birth. But the higher your blood pressure is, the more likely it is that your doctor will offer to start your labour artificially. This is called an induction.
Having an induction also depends on whether your high blood pressure is affecting your baby. Your doctor will discuss your case with you, mentioning any other complications, so that you can come to the right decision for you.
High blood pressure needs frequent monitoring during labour. If your high blood pressure is mild or moderate, you could have it measured hourly. If it is severe, it may need to be continuously monitored.
If you’re taking medication, you’ll need to carry on taking it during labour. Even so, it’s perfectly possible to aim for a straightforward birth, as long as your high blood pressure is well controlled during labour. Your baby will be continuously monitored, though, to make sure he doesn’t become distressed.
Some mums-to-be whose severe high blood pressure doesn’t respond to treatment may be offered an assisted birth. This means a doctor helps your baby to be born using instruments that attach to your baby’s head. This can speed up the second stage of labour.

What will happen after my baby is born?

Your blood pressure will be monitored at least daily for the first two days after your baby’s birth. It will then be checked at least once three days to five days after the birth.
If your blood pressure was normal before you became pregnant, it will most likely return to normal within a few weeks of your baby’s birth. It’s worth being aware that you’re more likely to develop high blood pressure in a future pregnancy, and later in life.
If it doesn’t return to normal then it’s unlikely you had gestational hypertension. What you have is essential chronic hypertension. This means your blood pressure will carry on being high after your baby is born. If that’s the case, your doctor will probably advise you to keep taking medication to ensure your blood pressure stays at a healthy level.
In most cases, your midwife will advise you about when you need to make an appointment with your GP to review your medication. This will happen before your six-week postnatal check-up. Rest assured if you are breastfeeding, there are many medications for high blood pressure that are also safe for your baby.
By living a healthy lifestyle, you can help keep your blood pressure in a healthy range and lower your risk for heart disease and stroke. A healthy lifestyle includes:

• Eating a healthy diet.
• Maintaining a healthy weight.
• Getting enough physical activity.
• Not smoking.
• Limiting alcohol use.