Pre-eclampsia and High Blood Pressure During Pregnancy
Topic Overview
What are high blood pressure and pre-eclampsia?
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). When high blood pressure starts after 20 weeks of pregnancy, it may be a sign of a very serious problem called pre-eclampsia.
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 more than 140 millimetres of mercury (mm Hg), or if the bottom number is more than 90 mm Hg. For example, blood pressure of 150/85 (say "150 over 85") or 140/95 is high. Or both numbers can be high, such as 150/95.
A woman may have high blood pressure before she gets pregnant. Or her blood pressure may start to go up during pregnancy.
If you have high blood pressure during pregnancy, you need to have checkups more often than women who do not have this problem. There is no way to know if you will get pre-eclampsia. This is one of the reasons that you are watched closely during your pregnancy.
High blood pressure and pre-eclampsia are related, but they have some differences.
High blood pressure
Normally, a woman’s blood pressure drops during her second trimester. Then it returns to normal by the end of the pregnancy. But in some women, blood pressure goes up very high in the second or third trimester. This is sometimes called pregnancy-induced hypertension. It needs treatment, but it usually goes away after the baby is born.
High blood pressure that started before pregnancy usually doesn't go away after the baby is born.
A small rise in blood pressure may not be a problem. But your doctor will watch your pressure to make sure it does not get too high. The doctor also will check you for pre-eclampsia.
Very high blood pressure keeps your baby from getting enough blood and oxygen. This could limit your baby’s growth or cause the placenta to pull away too soon from the uterus. High blood pressure also could lead to stillbirth.
Pre-eclampsia
Pre-eclampsia is new high blood pressure after 20 weeks of pregnancy along with other problems, such as protein in your urine. Pre-eclampsia usually goes away after you give birth. In rare cases, blood pressure can stay high for up to 6 weeks after the birth.
Pre-eclampsia can be deadly for the mother and baby. It can keep the baby from getting enough blood and oxygen. It also can harm the mother’s liver, kidneys, and brain. Women with very bad pre-eclampsia can have dangerous seizures. This is called eclampsia.
What causes pre-eclampsia and high blood pressure during pregnancy?
Experts don't know the exact cause of pre-eclampsia and high blood pressure during pregnancy. But they have some ideas about pre-eclampsia:
- Pre-eclampsia seems to start because the placenta doesn't grow the usual network of blood vessels deep in the wall of the uterus. This leads to poor blood flow in the placenta.
- Pre-eclampsia may run in families. If your mother had pre-eclampsia while she was pregnant with you, you have a higher chance of getting it during pregnancy. You also have a higher chance of getting it if the mother of your baby’s father had pre-eclampsia.
- The mother’s immune system may react to the father's sperm, the placenta, or the baby.
- Already having high blood pressure when you get pregnant raises your chance of getting pre-eclampsia.
- Problems that can lead to high blood pressure, such as obesity, polycystic ovary syndrome, and diabetes, could raise your risk of pre-eclampsia.
What are the symptoms?
High blood pressure usually doesn't cause symptoms. But very high blood pressure sometimes causes headaches and shortness of breath or changes in vision.
Mild pre-eclampsia usually doesn't cause symptoms, either. But pre-eclampsia can cause rapid weight gain and sudden swelling of the hands and face. Severe pre-eclampsia causes symptoms of organ trouble, such as a very bad headache and trouble seeing and breathing. It also can cause belly pain and decreased urination.
How are high blood pressure and pre-eclampsia diagnosed?
High blood pressure and pre-eclampsia are usually found during a prenatal visit. This is one reason why it’s so important to go to all of your prenatal visits. You need to have your blood pressure checked often. During these visits, your blood pressure is measured with a blood pressure cuff
. A sudden increase in blood pressure often is the first sign of a problem.
You also will have a urine test to look for protein, another sign of pre-eclampsia.
If you have high blood pressure, tell your doctor right away if you have a headache or belly pain. These signs of pre-eclampsia can occur before protein shows up in your urine.
How are they treated?
You may be able to keep your blood pressure under control with a balanced diet and mild exercise. In some cases, you may also need to take medicine. You probably will get medicine if your bottom blood pressure number is 105 or higher.
The only cure for pre-eclampsia is having the baby. You may get medicines to lower your blood pressure and to prevent seizures. You also may get medicine to help your baby’s lungs get ready for birth. Your doctor will try to deliver your baby when the baby has grown enough to be ready for birth. But sometimes a baby has to be delivered early to protect the health of the mother or the baby. If this happens, your baby will get special care for premature babies.
Do pre-eclampsia and high blood pressure lead to long-term high blood pressure?
If you have high blood pressure during pregnancy but had normal blood pressure before pregnancy, your pressure is likely to go back to normal after you have the baby. But if you had high blood pressure before pregnancy, you probably will still have it after you give birth.
Experts don't think pre-eclampsia causes high blood pressure later in life. But women who get pre-eclampsia may have a higher-than-normal chance of getting high blood pressure after pregnancy or later in life.1
Frequently Asked Questions
Learning about high blood pressure and pre-eclampsia during pregnancy:
Being diagnosed:
Getting treatment:
Ongoing concerns:
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| Author: | Shannon Erstad, MBA/MPH Carrie Henley | Last Updated: March 15, 2007 |
| Medical Review: | Joy Melnikow, MD, MPH - Family Medicine Anne C. Poinier, MD - Internal Medicine Gregory A L Davies, MD, FRCSC, FACOG - Maternal-Fetal Medicine William Gilbert, MD - Perinatology | |
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