What is Preeclampsia?

Preeclampsia

What is preeclampsia?

Preeclampsia is an illness that happens only in pregnancy and can affect both you and your baby. It starts with a problem in the placenta, which is the organ that joins you and your baby in your womb.

Nearly all women with preeclampsia get high blood pressure.

Getting high blood pressure while you're pregnant can be an early sign of preeclampsia.

For many women, preeclampsia is so mild that they don't even know they have it. But it can get bad enough to make you and your baby seriously ill. Preeclampsia doesn't get better until after your baby is born. So you may need to have your baby early.

Pregnancy can be stressful, so if you have preeclampsia as well it can be frightening. But with specialist care, most women have healthy babies and get better very quickly afterward. And most women who get preeclampsia have normal pregnancies next time.

Key points for women with preeclampsia

Preeclampsia is a serious illness that you can get when you are pregnant.
Doctors think it starts when the organ that joins you and your baby in the womb doesn't grow as it should. That organ is called the

placenta
The placenta is an organ that grows in the womb during pregnancy. It joins the woman to the growing baby. The placenta provides the baby with oxygen, water and nutrients from the mother's blood. It also produces the hormones that are involved in pregnancy.

placenta.
Because of this problem with the placenta, your baby may not get enough blood to grow properly.
Also, harmful chemicals from the placenta can get back into your bloodstream and make your

blood pressure
Blood pressure is the amount of force exerted by the blood on the walls of the vessels that carry it. You can think of it like the water pressure in your home: the more pressure you have, the faster and more forcefully the water flows out of the shower. Blood pressure is measured in millimeters of mercury (written as mm Hg). When your blood pressure is taken, the measurement is given as two numbers, for example 120/80 mm Hg. The first, higher, number is called the systolic pressure, and the second, lower, number is the diastolic pressure. The systolic number is the highest pressure that occurs while the heart is pushing blood into the arteries. The diastolic number is the lowest pressure that happens when the heart is relaxing and is not pushing the blood.

blood pressure high. You can have problems (complications) from this.
Most women with preeclampsia don't feel sick. So you need to go to all of your regular checkups when you are pregnant, to pick it up early.
If you get severe preeclampsia, you should stay in the hospital until your baby is born. You may need to have your baby early.
Having preeclampsia once doesn't mean you will get it again. Many women who've had preeclampsia have a normal pregnancy the next time.

The "pre" in preeclampsia means before. The "eclampsia" means

seizure
A seizure is a sudden spasm of muscles caused by too much electrical activity in the brain. It results in muscle twitching and other symptoms.

seizure. So, preeclampsia refers to the illness women get before it becomes so serious that they have a seizure. But the name is confusing because very few women with preeclampsia ever have a seizure. That's because doctors treat the illness or deliver the baby early to avoid any problems.

What happens in a normal pregnancy

To understand what goes wrong in preeclampsia, it helps to know something about what happens in a normal pregnancy.

The placenta nourishes your baby with nutrients and oxygen it takes from your blood.

Let's look at how the placenta grows in your womb. That's where things seem to go wrong in preeclampsia.

The placenta takes nutrients and oxygen from your blood to nourish your baby in your womb. So for a healthy pregnancy, the placenta needs a good supply of blood from you.

Source:
Redman CW, Sargent IL.
Latest advances in understanding pre-eclampsia.
Science. 2005; 308: 1592-1594.

Here are some of the changes that happen in your body to give the placenta enough blood.

During the first half of your pregnancy, blood vessels in your womb get much bigger.
These bigger blood vessels will carry blood to the placenta. To find out more, see How the placenta grows.
Your heart starts to pump out more blood with each heartbeat. It stays like this until your baby is born.

Source:
Weissgerber TL, Wolfe LA.
Physiological adaptation in early human pregnancy: adaptation to balance maternal-fetal demands.
Applied Physiology, Nutrition, and Metabolism. 2006; 31: 1-11.

²
Some of the extra blood flowing through your body goes to your womb to feed your baby.

What goes wrong in preeclampsia

We can't be sure about what goes wrong in preeclampsia. It's a complicated illness.

But what seems to happen is that the placenta doesn't get enough blood from you. This is because the blood vessels that go to the placenta don't grow properly.

Whether your baby is affected by this, and how badly, depends on how much blood gets through.

This problem in the placenta can affect both your baby and you.

Your baby may not grow as well as he or she should. That's because your baby can't get enough food from the placenta. For more, see Preeclampsia and your baby.
The unhealthy placenta sends harmful chemicals back into your bloodstream. The chemicals damage the lining of your blood vessels. This can cause

high blood pressure
Your blood pressure is considered to be high when it is above the accepted normal range. The usual limit for normal blood pressure is 140/90. If either the first (systolic) number is above 140 or the lower (diastolic) number is above 90, a person is considered to have high blood pressure. Doctors sometimes call high blood pressure "hypertension."

high blood pressure, problems with your

kidney
Your kidneys are organs that filter your blood to make urine. You have two of them, on either side of your abdominal cavity, toward your back.

kidneys, swelling and other problems.

Source:
Williams Obstetrics.
Hypertensive disorders in pregnancy.
McGraw-Hill, New York, USA; 2004-2005.

³ For more, see Preeclampsia and you.

No one knows what causes preeclampsia. But there are so many ideas that it has been called "the disease of theories." Probably more than one thing goes wrong.

The latest thinking is that two things have to happen together for a pregnant woman to get preeclampsia.

Source:
Roberts JM, Gammill HS.
Pre-eclampsia: recent insights.
Hypertension. 2005; 46: 1243-1249.

⁴

The woman has to have some things that increase her chances of getting preeclampsia. For example, she may have high blood pressure or

diabetes
Diabetes is a condition that causes too much sugar to circulate in your blood. It happens when your body stops making a hormone called insulin (type 1 diabetes) or when insulin stops working (type 2 diabetes).

diabetes or be overweight. Or she may be carrying twins or triplets. Or maybe preeclampsia runs in her family.
The placenta doesn't grow normally in the first half of pregnancy. This means not enough blood reaches the placenta in the second half of pregnancy.

Nearly all women with preeclampsia get high blood pressure. But not all women with high blood pressure get preeclampsia. You may hear high blood pressure during pregnancy called pregnancy-induced hypertension or gestational hypertension. It is not as serious as preeclampsia.

Source:
Roberts JM, Redman CWG.
Pre-eclampsia: more than pregnancy-induced hypertension.
Lancet. 1993; 341: 1447-1451.

⁵ But it can turn into preeclampsia at any time. For more, see Blood pressure during pregnancy.

Preeclampsia affects different women and their babies in different ways. Here is what we know.

It can affect you, your baby, or both you and your baby.
It can be so mild that you don't notice it. Or it can so severe that it puts both your lives in danger.
It usually happens in the last few weeks of pregnancy. But it can start any time from 20 weeks of pregnancy to during or even just after the birth.
It can come on very slowly, over weeks or months. Or it can get very bad in just a few days.

Why me?

We don't know for sure why some women get preeclampsia and others don't. But certain things make you more likely to get it. Things that make you more likely to get an illness are called risk factors.

There are lots of risk factors for preeclampsia. They include:

Source:
Duckitt K, Harrington D.
Risk factors for pre-eclampsia at antenatal booking: systematic review of controlled studies.
BMJ. 2005; 330: 565-567.

⁶

Being pregnant for the first time
Having had preeclampsia before
Having high blood pressure before you get pregnant
Having health problems, such as kidney problems or a condition called

rheumatoid arthritis
If you have rheumatoid arthritis, your joints get painful, swollen and stiff. Rheumatoid arthritis is caused by inflammation inside your joints. It happens when your immune system attacks the lining of your joints.

rheumatoid arthritis
Being older than 40
Carrying two or more babies.

For more, see Risk factors for preeclampsia.

Sources for the information on this page:

Redman CW, Sargent IL.Latest advances in understanding pre-eclampsia.Science. 2005; 308: 1592-1594.

Weissgerber TL, Wolfe LA.Physiological adaptation in early human pregnancy: adaptation to balance maternal-fetal demands.Applied Physiology, Nutrition, and Metabolism. 2006; 31: 1-11.

Williams Obstetrics.Hypertensive disorders in pregnancy.McGraw-Hill, New York, USA; 2004-2005.

Roberts JM, Gammill HS.Pre-eclampsia: recent insights.Hypertension. 2005; 46: 1243-1249.

Roberts JM, Redman CWG.Pre-eclampsia: more than pregnancy-induced hypertension.Lancet. 1993; 341: 1447-1451.

Duckitt K, Harrington D.Risk factors for pre-eclampsia at antenatal booking: systematic review of controlled studies.BMJ. 2005; 330: 565-567.

This information was last updated on Apr 14, 2009

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© BMJ Publishing Group Limited 2009. All rights reserved.

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