Patient information from BMJ

Preeclampsia: what is it?

Last published:Jul 24, 2020

Preeclampsia is an illness that women can get when they're pregnant. It includes having high blood pressure in the later stages of pregnancy, from about 20 weeks. For many women, it's so mild that they don't even know they have it. But preeclampsia always needs to be taken seriously. It can make you and your baby very ill.

What is it?

When you're pregnant, a mass of tissue called the placenta grows between you and your baby. It's there to feed the baby while it develops inside you.

Doctors think preeclampsia starts when the placenta doesn't grow as it should. When this happens your baby might not get enough food from the placenta. And the placenta can send harmful chemicals into your bloodstream that raise your blood pressure.

Preeclampsia can start at any time from about the 20th week of pregnancy.

If you have mild preeclampsia, you might just need some extra checkups. But if it's more serious you may need to stay in the hospital until your baby is born. You may even need to have your baby early.

Doctors don't really know what causes preeclampsia. But you have more chance of getting it if you:

• are over 40

• are overweight or obese

• have diabetes

• have had preeclampsia before, or

• are carrying more than one baby.

What are the symptoms?

Preeclampsia doesn't usually cause symptoms unless it gets serious. Any early signs can be picked up during your regular checkups. Signs include:

• high blood pressure

• more protein in your urine than normal, and

• swelling in your hands, face, or feet.

Although high blood pressure and swelling are signs of preeclampsia, they do not always mean that you have preeclampsia. For example, many women have some mild swelling during pregnancy, especially in the ankles, feet, and hands.

If you have preeclampsia your baby might not be growing fast enough. Doctors can see this on an ultrasound scan.

If preeclampsia gets bad, it can cause serious health problems. Signs include:

• vomiting

• a bad headache

• blurred or double vision, or flashing lights before your eyes, and

• a bad pain just under your ribs.

If you get any of these, or if you're worried for any reason, see your doctor or midwife right away.

What will happen to me?

If you have preeclampsia your doctor may suggest medications to lower your blood pressure. You may need to go to the hospital to rest until your baby is born. Preeclampsia doesn't get better until after your baby is born.

To read more about treatments for preeclampsia, see our leaflet Preeclampsia: what treatments work?

If you get preeclampsia near the end of your pregnancy you may be able to give birth naturally. Otherwise, you'll probably need to have your baby early.

If you get severe preeclampsia at 34 weeks or later your baby will probably be delivered as soon as your doctor thinks is safe. If you get bad preeclampsia earlier than this you may be looked after in the hospital for a while. This is to give your baby more time to grow.

Some women get serious health problems because of preeclampsia. These include seizures, or problems with their liver, kidneys, heart, or lungs.

But these problems are rare these days. The care women get during pregnancy helps to pick up preeclampsia before it gets dangerous. Doctors can usually pick up problems before they harm your baby.

Most women who've had preeclampsia get back to normal health after they have their baby. You may need to recover in the hospital for a few days.

The care your baby will need depends on lots of things, such as how early he or she was born, and how small he or she is. Being born very early usually means babies need more medical care.

Having preeclampsia once increases your chance of having it in your next pregnancy. But most women who've had preeclampsia don't get it again.

In your next pregnancy you should be cared for by a specialist doctor. You will need to have more frequent checkups than usual.