High Blood Pressure During Pregnancy

Topic Overview

Is this topic for you?

This topic is about high blood pressure that some women get while they are pregnant. For information about pre-eclampsia, a more serious kind of high blood pressure, see the topic Pre-Eclampsia.

What is high blood pressure?

Blood pressure is a measure of how hard your blood pushes against the walls of your arteries. If the force is too hard, you have high blood pressure (also called hypertension).

Blood pressure is shown as two numbers. The top number (systolic) is the pressure when the heart pumps blood. The bottom number (diastolic) is the pressure when the heart relaxes and fills with blood.

Blood pressure is high if the top number is 140 or higher or if the bottom number is 90 or higher.

Blood pressure during pregnancy

Normally, a woman's blood pressure drops during her second trimester. Then it returns to normal by the end of the pregnancy.

But some women have high blood pressure while they are pregnant. They may have:

  • High blood pressure that started before pregnancy. This is called chronic high blood pressure. It usually doesn't go away after the baby is born.
  • Very high blood pressure that starts in the second or third trimester. This is called gestational hypertension. It usually goes away after the baby is born.

Sometimes high blood pressure during pregnancy is a first sign of pre-eclampsia. This condition can be dangerous for both mother and baby.

Having high blood pressure during pregnancy doesn't mean that you will get pre-eclampsia. But it does mean that you need to have your blood pressure checked often. And you may need treatment.

Why is high blood pressure during pregnancy a concern?

If your blood pressure is very high, it could keep your baby from getting enough blood and oxygen. This could limit your baby's growth, or it could cause the placenta to pull away from the uterus too soon. (This is called abruptio placenta.) It also increases risk of stillbirth.

What are the symptoms?

High blood pressure doesn't usually cause symptoms. You will probably feel fine, even if your blood pressure is too high.

Tell your doctor right away if you have any signs of very high blood pressure or pre-eclampsia, such as:

  • A severe headache.
  • Blurry vision.
  • Pain in your upper belly.
  • Rapid weight gain—more than 1 kg (2 lb) in a week or 3 kg (6 lb) in a month.

How is high blood pressure diagnosed?

High blood pressure is usually found during a prenatal visit. This is one reason it's so important to go to all of your prenatal checkups.

At each prenatal visit, your doctor, nurse, or midwife will:

  • Check your blood pressure. A sudden increase in blood pressure often is the first sign of a problem.
  • Test your urine for protein. Too much protein in the urine is a sign of kidney damage caused by pre-eclampsia.
  • Check your weight. Rapid weight gain can be a sign of pre-eclampsia.

If you have high blood pressure while you're pregnant, you will have regular tests to check your baby's health. These may include:

  • Electronic fetal heart monitoring. This records your baby's heart rate.
  • Fetal ultrasound. This test is done to check on your baby, the placenta, and the amount of amniotic fluid.
  • Doppler ultrasound. This checks how well the placenta is working.

If your doctor thinks you are at high risk for pre-eclampsia, you may have other tests, including:

  • Blood tests to check for problems such as kidney damage.
  • A creatinine clearance test to check your kidney function.

How is it treated?

You may need to take medicine if your doctor thinks your blood pressure is too high. Medicines used to treat high blood pressure during pregnancy include methyldopa and nifedipine.

Some common blood pressure medicines are not safe during pregnancy. If you take medicine for chronic high blood pressure:

  • Talk to your doctor about the safety of your medicine before you become pregnant or as soon as you learn you are pregnant.
  • Be sure that your doctor has a complete list of all the medicines you take.

If you are at high risk for pre-eclampsia, your doctor may recommend that you take low-dose aspirin and a calcium supplement during your pregnancy.footnote 1

What can you do to take care of yourself?

To help control your blood pressure and have a healthy pregnancy:

  • Be sure to go to all of your prenatal checkups so your doctor or midwife can check your blood pressure. You may also want to check your blood pressure at home.
  • Don't smoke. This is one of the best things you can do to lower your blood pressure and to help your baby be healthy. If you need help to quit smoking, talk to your doctor.
  • Gain an amount of weight that is healthy for you. Your doctor or midwife can help you set a pregnancy weight goal.
  • If your doctor says it's okay, get regular exercise during pregnancy. Walking or swimming several times a week can help lower blood pressure. And it's good for you and your baby.
  • Try to keep your stress level low. This may be hard to do, especially if you continue to work, have young children, or have a hectic schedule. But try to find some time to relax.

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Other Places To Get Help


Society of Obstetricians and Gynaecologists of Canada (SOGC)
Hypertension Canada: Understanding Hypertension



  1. Magee LA, et al. (2014). Diagnosis, evaluation, and management of the hypertensive disorders of pregnancy: Executive summary. SOGC Clinical Practice Guideline No. 307. Journal of Obstetrics and Gynaecology Canada, 36(5): 416–438. http://sogc.org/wp-content/uploads/2014/05/gui307CPG1405E1.pdf. Accessed June 26, 2014.

Other Works Consulted

  • American College of Obstetricians and Gynecologists (2012). Chronic hypertension in pregnancy. ACOG Practice Bulletin No. 125. Obstetrics and Gynecology, 119(2): 396–407.
  • Campbell NRC (2015). Hypertension. Compendium of Therapeutic Choices. Ottawa: Canadian Pharmacists Association. https://www.e-therapeutics.ca. Accessed March 30, 2016.
  • U.S. Preventive Services Task Force (2014). Low-dose aspirin use for the prevention of morbidity and mortality from preeclampsia: U.S. Preventive Services Task Force recommendation statement. U.S. Preventive Services Task Force. http://www.uspreventiveservicestaskforce.org/uspstf/uspsaspg.htm. Accessed September 16, 2014.


Adaptation Date: 2/21/2019

Adapted By: HealthLink BC

Adaptation Reviewed By: HealthLink BC

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