High blood pressure in pregnancy is a common medical problem that usually disappears once the baby is born. In some cases, it can signal a serious condition called pre-eclampsia.
Your blood pressure is a measure of how strongly your blood pushes against the walls of the blood vessels. It’s normally recorded in 2 numbers: the top one (systolic) is the pressure when the heart is pumping, and the bottom one (diastolic) is the pressure in between each beat.
When you are pregnant, you are considered to have high blood pressure when the top number is 140 or more or the bottom number is 90 or more (described as “140 over 90”). High blood pressure is sometimes called hypertension.
Seek medical attention urgently if you have high blood pressure in pregnancy along with:
- a severe headache
- blurred vision
- sudden swelling of the face, hands and feet
- a pain in your upper abdomen (just below the ribs)
Different types of high blood pressure in pregnancy
There are 3 types of high blood pressure during pregnancy:
- Chronic hypertension: This is when you already had high blood pressure before you fell pregnant – for example if you already had a medical condition such as kidney disease. Chronic hypertension also refers to when your high blood pressure is diagnosed in the first 20 weeks of pregnancy. Some women with chronic hypertension may develop pre-eclampsia when they are pregnant.
- Pregnancy-induced hypertension: This is high blood pressure that is diagnosed after 20 weeks of pregnancy. It is also called ‘gestational hypertension’.
- Pre-eclampsia: Pre-eclampsia is a serious condition that only occurs in pregnant women. As well as high blood pressure, it can also affect the kidneys, liver, blood and brain.
What causes high blood pressure during pregnancy?
Any woman can develop high blood pressure during their pregnancy, but you are at increased risk if:
- you have had pre-eclampsia before
- close relatives have had pre-eclampsia
- you have a medical condition such as kidney disease, diabetes or chronic hypertension
- you are older than 40
- you are obese
- you are carrying twins or more
Can high blood pressure affect the baby?
High blood pressure in pregnancy can prevent blood from flowing to the placenta. Because the baby doesn’t get enough nutrients or oxygen, they are at higher risk of being low birth weight or being born prematurely.
For this reason, it’s very important that high blood pressure is picked up early and treated.
What are the effects of high blood pressure on the mother?
Untreated high blood pressure during pregnancy increases the risk of placental abruption, preterm labour, gestational diabetes or stillbirth.
Women who experience high blood pressure in pregnancy are more likely to have problems with high blood pressure and heart disease in later life.
Treatments for high blood pressure
Your doctor or midwife will check your blood pressure regularly. If you have high blood pressure, it is important to:
If high blood pressure is caused by a medical condition such as kidney disease, it’s important to talk to your doctor about what medications are safe to take during pregnancy.
Pre-eclampsia can be managed with medication and close monitoring of both you and the baby. However, it can become worse very quickly. If this happens, you may need to go to hospital or have the baby delivered early.
How high blood pressure impacts labour and birth
If you have high blood pressure, both you and your baby will be closely monitored during the pregnancy. During labour, the baby’s heart will be continuously monitored and you may have an intravenous drip to give you fluid and medication. If your condition seems to be worsening during labour, you may need an emergency caesarean.
If you have pre-eclampsia, it will normally be recommended that you have the baby in a large maternity hospital which can provide expert care for both mother and baby. It may mean the baby is born early or is smaller than expected.
Does blood pressure remain high after the birth?
High blood pressure in pregnancy usually disappears once the baby is born. However, there may still be some complications during the first few days after the birth and you will need to be monitored carefully for several weeks.
Women who had high blood pressure due to another condition (chronic hypertension) will need to see their doctor to make sure their blood pressure returns to safe levels.
Are there any implications for future pregnancies?
Having high blood pressure in pregnancy doesn’t necessarily mean you will develop high blood pressure in future pregnancies. However, your risk is increased, especially if you have a medical condition like hypertension, kidney disease, diabetes or lupus.
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Last reviewed: January 2020