High blood pressure in pregnancy

High blood pressure in pregnancy

Your blood pressure will be closely monitored at your antenatal appointments. High blood pressure affects 10-15% of pregnant women and can have serious consequences if it's not properly controlled. Find out what symptoms you should look out for, and how it can be treated in pregnancy.

Your blood pressure refers to the force with which your blood is pushed around your body by your heart. If you have high blood pressure, your blood vessels and organs are under extra pressure and this puts you at increased risk of a heart attack or stroke. If you're pregnant, high blood pressure can also lead to serious complications including pre-eclampsia.

How will my blood pressure be checked?

If you've ever been on the pill or had other health checks before pregnancy, then you might well have had your blood pressure measured already. During pregnancy, your blood pressure will be checked at all your appointments.

For the unacquainted, the process is very simple and non-invasive. The nurse or midwife will fasten an inflatable cuff around your upper arm. This will inflate and might feel a bit tight, but it shouldn’t be painful. You should try to relax as much as you can and not move, or it'll have to be taken again. The air in the cuff will then be slowly released and the nurse or midwife will be given a reading of millimetres of mercury (mm/Hg). This will look a little like a fraction eg 115/75.

The top number is called the “systolic” pressure and measures the pressure of the blood being pushed around your body. The second number is called the “diastolic” pressure which measures how much your heart relaxes between beats. It is this second number that is the more important one.

High blood pressure

It's normal for your blood pressure to go up and down a little during pregnancy and what's normal for you may not be the same as the next person. But, generally speaking, an average healthy blood pressure reading for someone who is pregnant falls between 110/70 and 120/80.

High blood pressure in pregnancy comes in two forms:

How high does my blood pressure have to be for it to be “high”?

In these two types of hypertension, there are three levels:
  • Mild hypertension – between 140/90 and 149/99 mm Hg
  • Moderate hypertension – between 150/100 and 159/109
  • Severe hypertension – 160/110 or higher

Treating high blood pressure in pregnancy

If you have mild hypertension then you'll likely be monitored closely throughout pregnancy, but you probably won't need any treatment. If it's on the higher end, then you may be prescribed medication to try and lower your blood pressure, depending on your needs and what's causing the high blood pressure.

Controlling high blood pressure

I changed my diet to virtually no meat and daily legumes, whole grains and veggies. I cook from scratch with very little salt and try to keep sugar consumption down too.

You should try to keep active by exercising during pregnancy. And of course, a healthy diet during pregnancy is very important anyway.

There are plenty of dos and don'ts when it comes to food when you're expecting. If you have high blood pressure, then you should limit your salt intake as well, as this has been shown to help lower blood pressure.

What are the symptoms of high blood pressure?

High blood pressure usually has no symptoms and is picked up during a routine antenatal appointment. But you should be aware of the symptoms of pre-eclampsia just in case – as these are indicative of something more serious going on.

Blood pressure nurse woman

Is high blood pressure dangerous?

It can be, but it's rare that it is. As long as hypertension is picked up and monitored properly, you shouldn't need to worry – if anything, worrying about it will only raise your blood pressure (a vicious circle). Most mild to moderate cases will only need keeping an eye on and won't cause you serious harm.

That said, you should be aware that problems relating to hypertension are more likely to develop if you have high blood pressure earlier in your pregnancy.

Gestational hypertension

Around 16% of pregnant women experience pregnancy-induced high blood pressure. According to the NHS, this typically occurs in late pregnancy – from 32 weeks onwards.

Gestational hypertension can be a sign that pre-eclampsia is developing – a serious condition that restricts the amount of oxygen that reaches the placenta. It affects around 6% of pregnancies and 1-2% of pregnant women will suffer from a more serious form.

Early symptoms include high blood pressure and traces of protein in your urine (which is why you usually have to pee in a pot at doctors appointments).

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.

Symptoms of pre-eclampsia

  • Severe headaches
  • Dizziness
  • Visual disturbance (including temporary loss of vision)
  • Vomiting
  • Sudden fluid retention
  • Puffiness in the face, hands and feet
  • Upper abdominal pain
  • General malaise (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.

Should I worry if I have chronic high blood pressure?

High blood pressure is like having a black cloud over your head sometimes, but monitoring it regularly is the way to go.

If you were told you had high blood pressure before you hit the 20-week mark, then it'll be considered as existing before you got pregnant – so-called “chronic high blood pressure.” Blood pressure commonly drops in the first half of pregnancy, so if you have chronic hypertension and are already taking medication for your blood pressure then it is possible that your medication will stop, at least temporarily.

Some blood pressure medications are not recommended in pregnancy, so if you have chronic hypertension for which you are receiving treatment, you should consult your doctor before trying to conceive.

Certain drugs that reduce blood pressure can also reduce blood flow to the placenta, so you should be sure to attend all your antenatal appointments for monitoring if you take them.

Will high blood pressure affect my labour or birth?

If you take medication to control your high blood pressure, you should keep taking it during labour. Your blood pressure will be monitored hourly during labour if you have mild to moderate hypertension. You can hope for a natural vaginal birth if your blood pressure remains within target levels.

During both my pregnancies I suffered with high blood pressure (not pre-eclampsia) but it returned to normal days after delivery.

If you have severe hypertension, then your levels will be monitored continuously during labour. You may be recommended an operative delivery (using forceps or ventouse) or a c-section.

After you have given birth, your blood pressure will continue to be monitored for a while. If you have chronic hypertension, you should be checked over about two weeks after the baby is born. Mothers who have gestational hypertension for which treatment is required should be offered an appointment to see if treatment should be changed or stopped after pregnancy.

If you've had any sort of hypertension (chronic or gestational) during pregnancy, then it should be checked at your postnatal check which takes place around six weeks after the baby is born.

Will I still be able to breastfeed if I take medication to control my blood pressure?

There is limited evidence on whether anti-hypertensive drugs pass into breastmilk or not. Talk to your doctor or midwife to check about medication before your start breastfeeding.