When your doctor checks your blood pressure and asks for a urine sample at each prenatal visit, he or she is partly checking for signs of preeclampsia. While pregnancy-induced high blood pressure isn’t very common, left untreated, it can lead to potentially dangerous complications for both you and your baby.

Fortunately, the condition is almost invariably caught early on and managed successfully, as long as you’re receiving regular medical care. With appropriate and prompt treatment, women with preeclampsia late in pregnancy have virtually the same excellent chance of having a healthy pregnancy and baby as those with normal blood pressure.

What is preeclampsia?

Preeclampsia is a disorder that generally develops after week 20 of pregnancy and is characterized by a sudden onset of high blood pressure. You may or may not also experience other symptoms, including protein in the urine and severe swelling of the hands and face. 

When the condition — also known as pregnancy-induced hypertension (PIH) or toxemia — is diagnosed before 32 weeks of pregnancy, it’s referred to as early-onset preeclampsia.

Unmanaged preeclampsia can prevent a developing fetus from getting enough blood and oxygen and damage a mother's liver and kidneys.

In rare cases, untreated preeclampsia can progress to eclampsia, a much more serious condition involving seizures, or HELLP, another serious syndrome that can lead to liver damage and other complications.

How common is preeclampsia?

An estimated 5 to 8 percent of pregnant women in the U.S. are diagnosed with preeclampsia. The condition tends to be more common in Black and Hispanic women than white women.

Who is most at risk of having preeclampsia?

Preeclampsia is more common in first pregnancies, which are generally classified as high-risk once the condition is identified.

If you’ve been diagnosed with preeclampsia in a previous pregnancy, there’s a roughly 1 in 3 chance of developing the condition in a future pregnancy. The risk increases the earlier you’re diagnosed in your pregnancy, or if you’re diagnosed with preeclampsia during your first pregnancy.

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The following factors have also been connected with women who are diagnosed with preeclampsia: 

What are the symptoms of preeclampsia?

At each prenatal visit, your practitioner should check you for the following signs of preeclampsia:

  • A rise in blood pressure (to 140/90 or more) if you’ve never had high blood pressure before
  • Protein in the urine
  • Severe swelling of the hands and face
  • Severe swelling of the ankles (edema) that doesn’t go away
  • Severe headache that doesn’t respond to acetaminophen (Tylenol)
  • Vision changes, including blurred or double vision
  • Sudden excessive weight gain unrelated to eating
  • Abdominal pain, particularly in the upper abdomen
  • Rapid heartbeat
  • Scant or dark urine
  • Exaggerated reflex reactions
  • Abnormal kidney function
  • Lower levels of platelets in your blood (thrombocytopenia)
  • Abnormal nausea or vomiting 
  • Shortness of breath caused by fluid in the lungs

Many symptoms of preeclampsia, like weight gain and edema, can be normal in a perfectly healthy pregnancy. That’s why it’s so important to regularly see your doctor, who can monitor symptoms and, if necessary, order tests to make a definitive diagnosis.

Also keep in mind that high blood pressure on its own, whether you had it before pregnancy or it developed following conception, is not preeclampsia.  

What causes preeclampsia?

No one knows for sure what causes preeclampsia, although experts believe it begins in the placenta as your body amps up your blood production to support your growing baby. A decreased blood supply to the placenta in some women may lead to preeclampsia. 

There are a number of theories for preeclampsia causes, including:

  • A genetic link. The genetic makeup of a fetus could predispose a pregnancy to preeclampsia. That means if your mother or your partner’s mother had preeclampsia during their pregnancies with either of you, you may be somewhat more likely to have it yourself when you're expecting. Because a family history also increases the risk, your own genetics may play a role as well. 
  • A blood vessel defect. During pregnancy your body has to create extra blood vessels to send blood to your baby and placenta. In some women, these cells don’t develop or function properly, leading to preeclampsia. Since having preeclampsia during pregnancy increases the risk of having a cardiovascular condition later in life, faulty blood vessels might indicate a predisposition to high blood pressure in some women.
  • Gum disease. Having severe gum disease more than doubles the likelihood of a preeclampsia diagnosis. Experts don’t know if periodontal disease itself causes preeclampsia or if the conditions are simply linked. But they think it may be that the infection causing gum disease migrates to the placenta or produces chemicals that cause preeclampsia. 
  • An immune response. The baby and placenta are both foreign objects that seep up nutrients from your body. It’s possible that in women with preeclampsia, the body becomes sensitized to these “invaders” and reacts in a way that can damage blood and blood vessels. Having a partner with more similar genetic markers seems to increase the likelihood of this response.

How is preeclampsia diagnosed?

Regular prenatal care is the best way to catch preeclampsia in its early stages. Being alert to preeclampsia symptoms and alerting your practitioner if you notice them, especially if you have a history of hypertension before pregnancy, helps your doctor diagnose the condition sooner. 

Your doctor is not looking for one symptom but a pattern of symptoms. Protein in the urine, for example, is a symptom — but it doesn’t necessarily mean you have preeclampsia. 

If your practitioner suspects you have preeclampsia, he or she will give you blood and urine tests. Your doctor will also check to see how well your blood clots and may perform an ultrasound and fetal monitoring to ensure the health of your baby.

To make a preeclampsia diagnosis, your health care provider will look for the following symptoms:

  • High blood pressure (more than 140/90 mm Hg) 
  • Protein in your urine (proteinuria)
  • Other signs of kidney problems
  • A blood platelet count of less than 100,000 mL
  • Abnormally high liver enzymes, suggesting impaired liver function
  • Fluid in the lungs (pulmonary edema)
  • New headaches or visual disturbances

What are the possible complications of untreated preeclampsia?

If preeclampsia is left untreated, it can:

  • Progress to eclampsia, a much more serious pregnancy condition that results in seizures and other more serious consequences for you and your baby
  • Cause HELLP syndrome, another more serious condition that can result in complications including liver damage without prompt treatment. HELLP, which can happen on its own during pregnancy or in conjunction with preeclampsia, is characterized by low red blood cell count, elevated liver enzymes and clotting problems.
  • Cause preterm delivery
  • Cause intrauterine growth restriction (IUGR)
  • Cause placental abruption, or early separation of the placenta from the wall of the uterus
  • Damage your liver and kidneys

Having preeclampsia puts you at greater risk later in life of kidney disease and heart disease, including heart attack, stroke and high blood pressure. It also puts you at a higher risk of developing preeclampsia in subsequent pregnancies.

Remember, as long as you’re regularly seeing your doctor, you’ll receive a prompt diagnosis and treatment — which gives you the same great odds of having a healthy pregnancy and birth as women with normal blood pressure.

Can you prevent preeclampsia?

As with most pregnancy-related complications, the best way to prevent preeclampsia is to keep up on all your prenatal appointments, where you can bring up any conditions you’re experiencing and your doctor can do a thorough exam. Other ways to decrease your risk of preeclampsia include:

  • Eating healthy. That means watching your caloric intake (most pregnant women only need 300 to 500 extra calories a day staring in the second trimester and if pregnant with twins or multiples 600 extra calories a day), with plenty of high-fiber fruits and vegetables, whole grains, low-fat protein and dairy. Good intake of magnesium, in particular, may reduce preeclampsia risk (a square of dark chocolate is a surprisingly good source). Aim to limit or avoid foods that aren’t healthy for any pregnancy, such as sugary or processed foods.
  • Exercising. Talk to your doctor about how much exercise you should be getting; many suggest 30 minutes of moderate activity (such as a walk after lunch and dinner) a day.
  • Watching your weight. Gaining the recommended amount of weight during pregnancy has lots of benefits for you and your baby, including reducing your risk of preeclampsia. Keep in mind that while it’s helpful to lose weight before you conceive if you’re overweight or obese, it’s never a good idea to try and lose weight during pregnancy. One study of women with a history of preeclampsia found that weight loss between pregnancies reduced the risk of recurrent preeclampsia in those who were of normal weight, overweight or obese.
  • Managing chronic conditions. Chronic hypertension and diabetes are risk factors for preeclampsia, so it’s important to work with your doctor to keep these under control.
  • Talking to your doctor about aspirin. For high-risk women — those who’ve had preeclampsia in a previous pregnancy, are carrying multiples, have an autoimmune disease, or have high blood pressure or diabetes at the outset of pregnancy — taking a low-dose aspirin (81 mg) a day starting at week 12 of pregnancy may reduce preeclampsia risk. Before you take any medications during pregnancy, check with your doctor.
  • Caring for your teeth. Some research has indicated that women with a history of periodontal disease are at increased risk of preeclampsia. So to be on the safe side, maintain good oral hygiene before and during pregnancy, which includes flossing daily and visiting your dentist every six months.
  • Taking your prenatal vitamin. One more reason to pop that prenatal vitamin every day: It contains vitamin D, and some research has indicated that being vitamin D deficient increases your risk of preeclampsia, although other studies haven’t made the connection. Ask your doctor whether vitamin D supplements could lower your chances of getting preeclampsia. Calcium defiency has also been linked to a higher risk of the condition, so taking your prenatal every day will also ensure that you're getting enough of that nutrient. If you don't have enough calcium in your diet or vitamin, check with your practitioner to see whether a calcium supplement might be in order.

How preeclampsia is treated

It’s important to get treated for preeclampsia right away to keep it from progressing to a more serious condition like eclampsia or HELLP syndrome. 

While you can keep preeclampsia in check during pregnancy, the "cure" begins with delivering your baby and the placenta. Before then, treatments to manage preeclampsia depend on the severity of the condition.

For mild cases

In 75 percent of cases, preeclampsia is mild, though it can progress to severe preeclampsia or eclampsia quickly if it’s not promptly diagnosed and treated. 

Your doctor will probably recommend the following measures:

  • Regular blood and urine tests to check platelet counts, liver enzymes, kidney function and urinary protein levels that indicate whether the condition is progressing
  • A daily kick count in the third trimester
  • Blood pressure monitoring
  • Dietary changes, including eating more protein, veggies, fruits and low-fat dairy and less salt and drinking at least eight glasses of water a day
  • Possibly medication to lower your blood pressure (antihypertensives)
  • Possibly some form of bed rest, with the goal of prolonging the pregnancy until labor and delivery is safer 
  • Possible initial hospitalizations to monitor the progression or stability of the symptoms, along with the possible administration of corticosteroids to help improve fetal development
  • Early delivery (with induction or possibly C-section) as close to 37 weeks as possible

For more severe cases 

In severe preeclampsia, your blood pressure is much higher on a more regular basis. Managing the condition helps reduce the risk of organ damage and other more serious complications.

You’ll usually be treated in the hospital, where your doctor may suggest:

  • Careful fetal monitoring, including nonstress tests, ultrasounds, heart rate monitoring, assessment of fetal growth and amniotic fluid assessment
  • Medication to lower your blood pressure (antihypertensives)
  • The anticonvulsant medication magnesium sulfate, an electrolyte that may help prevent progression to eclampsia
  • Early delivery, often once you’ve reached 34 weeks of pregnancy and your condition is stable; your doctor may give you corticosteroids to help mature your baby’s lungs to deliver him right away, regardless of gestational age

Preeclampsia after birth

Most cases of preeclampsia resolve at baby’s birth. Rarely, preeclampsia symptoms appear within 48 hours after delivery, although postpartum preeclampsia can happen up to six weeks following a baby’s arrival. It’s more common in those who had preeclampsia during pregnancy, affecting an estimated 4 to 6 percent of those women.

Postpartum preeclampsia symptoms are similar to those you’d experience during pregnancy (including high blood pressure and vision changes). It’s essential to let your doctor know if you notice these symptoms.

Left untreated, postpartum preeclampsia can cause many of the same complications as prenatal preeclampsia (such as progression to eclampsia and HELLP syndrome). Your doctor will likely treat you with blood pressure medications along with magnesium sulfate to prevent seizures.