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Preeclampsia: What is it and how does it affect pregnancy?

Preeclampsia: What is it and how does it affect pregnancy?

10 min read

Preeclampsia is a condition that impacts up to 4.6% of pregnancies worldwide. Since preeclampsia is a pregnancy-specific condition, if you're not pregnant, you might be familiar with the term without really knowing what it means.

So, what exactly is preeclampsia? In this article, we'll cover what you need to know about the condition, what symptoms may come with it, how it's diagnosed and treated, and what can be done to reduce the risk.

The biggest takeaways

  • Preeclampsia is a condition only seen in pregnancy and the immediate postpartum period. It's marked by high blood pressure and organ damage. Hypertensive disorders during pregnancy, preeclampsia included, can lead to adverse outcomes for both the pregnant person and the fetus.
  • Preeclampsia is diagnosed when blood pressure is high and there's evidence of proteins in the urine (signaling organ damage).
  • Preeclampsia with severe features is diagnosed when blood pressure is very high and there are related issues (like abnormal lab values and certain symptoms like headache, vision changes, trouble breathing, or abdominal pain).
  • Treatment for preeclampsia is ultimately delivery of the infant. If you're too early in pregnancy to deliver, managing preeclampsia (through close monitoring and blood pressure medications) may be the best option.
  • There are possible long-term effects of developing preeclampsia in pregnancy, and the risks vary based on the severity of the condition.
  • There's no screening test that can predict preeclampsia. But if you have high blood pressure and you're thinking about trying to get pregnant, your healthcare provider can help you decrease this risk and understand what symptoms to look out for.

“Luckily, there’s a lot of focus on preventing preeclampsia within the medical community," says OB-GYN and Modern Fertility medical advisor Dr. Jenn Conti, MD, MS, MSc. "We have great tools, like taking aspirin daily after 12 weeks, that can help high-risk patients decrease their chances of developing this condition."

First, let's talk about pregnancy and blood pressure

Getting your blood pressure checked will be a regular part of your prenatal check-ups, and you can also check it at home if you have a blood pressure cuff.

Blood pressure is recorded as two numbers:

  • The top (systolic) number measures the amount of pressure your blood exerts on the artery walls when your heart is beating.
  • The bottom (diastolic) number measures the same thing — but when the heart is resting.

The American College of Obstetricians and Gynecologists recommends that blood pressure during pregnancy be less than 120/80 mm Hg. High blood pressure during pregnancy (we'll cover the specifics around preeclampsia in a bit), which is over 140 mm Hg (systolic) and over 90 mm Hg (diastolic), can lead to a number of adverse outcomes for both the pregnant person and the fetus:

  • Decreased blood flow to the placenta, which can result in fewer nutrients and lower oxygen getting to the fetus, as well as decreased fetal growth, lower birth weight, and premature birth.
  • Placental abruption, a condition in which the placenta separates from the inner wall of the uterus before delivery. This can cause heavy bleeding and be life-threatening to the pregnant person and fetus.
  • Injury to major organs, such as the brain, heart, lungs, kidneys, and liver.
  • Premature delivery due to complications that can prove life-threatening to the pregnant person and fetus.
  • If you've had high blood pressure or preeclampsia in pregnancy, you're at risk for cardiovascular disease in the future.

As we'll explain in the next section, preeclampsia is a condition that's associated with high blood pressure during pregnancy — as well as the same adverse outcomes listed above.

What is preeclampsia? Here are the basics

Preeclampsia is a condition (only seen in pregnancy and the immediate postpartum period) marked by high blood pressure and organ damage. While preeclampsia is a vascular issue (aka arteries and veins) at its core, it can also affect the brain, lungs, kidneys, and liver.

If preeclampsia is left uncontrolled, the condition can have a serious impact on the health of the pregnant person and the fetus.

For the pregnant person: Preeclampsia (as well as other hypertensive disorders during pregnancy) is one of the top causes of maternal deaths in the US and is responsible for up to 10%-15% of maternal deaths worldwide. Other complications include eclampsia (seizures from extremely high blood pressure) and a condition called HELLP. HELLP stands for hemolysis (the destruction of red blood cells), elevated liver enzymes, and low platelet count. 10% to 20% of pregnant people who have severe preeclampsia develop HELLP, but it usually reverses after delivery.

“People who have had preeclampsia with a past pregnancy have almost double the risk for heart disease and stroke over their next five to 15 years,” adds Dr. Conti. “This is why it’s vital that anyone who has had preeclampsia in the past works closely with their primary care provider or a cardiologist who can help optimize their health going forward.”

For the fetus: Preeclampsia can prevent proper nutrient transport to the fetus. Because of this, it’s not uncommon to see intrauterine growth restriction (IUGR). This occurs when the fetus falls under the tenth percentile on growth charts due to poor nutrient transport from placenta to the fetus.

(A little history: The term “eclampsia” actually comes from the Greek word for “thunder,” and was first used to describe the condition in 1619. However, there is written evidence from Hippocrates in the fourth century describing “a headache accompanied by heaviness and convulsions during pregnancy.)

What are the symptoms of preeclampsia?

Here’s the thing: Preeclampsia can be a difficult condition to diagnose because it’s multifactorial. Symptoms of elevated blood pressure might make a provider look closer, but more labs and monitoring are needed before a diagnosis can be made. This is why it's important to reach out to your healthcare provider ASAP if you experience any of the following symptoms (especially in the second half of pregnancy):

  • Sudden swelling of face or hands
  • Headache that won't go away
  • Seeing spots or changes in eyesight
  • Pain in the upper-mid or upper-right abdomen
  • New nausea and vomiting in the second half of pregnancy
  • Sudden weight gain
  • Difficulty breathing

Signs that you could have worsening preeclampsia include the following "severe features":

  • A low number of platelets in the blood
  • Abnormal kidney or liver function blood tests (creatinine, AST, ALT)
  • Pain in the upper abdomen
  • Changes in vision
  • Fluid in the lungs causing sudden shortness of breath
  • Severe, continuous headache
  • Systolic pressure of 160 mm Hg or higher or diastolic pressure of 110 mm Hg or higher

It’s important to come to your prenatal visits as frequently as your provider advises, since this is the opportunity to gather information, potentially diagnose any issues, and provide care. While prenatal visits may feel quick, a lot of information can be gathered from your blood pressure, urine, and straight from your mouth. It’s always important to tell your provider if you’re experiencing anything unusual.

What causes preeclampsia and what are the risk factors?

The medical community isn't totally sure what exactly causes preeclampsia. "The leading theory is that it has something to do with abnormal placentation — the way the placenta develops — that is likely related to some predisposing genetic factors," says Dr. Conti. There are also some risk factors to be aware of.

These factors can put you at a high risk for preeclampsia:

  • Preeclampsia in a past pregnancy
  • Pregnancy with multiples (twins, triplets)
  • Chronic hypertension
  • Kidney disease
  • Diabetes
  • Autoimmune conditions (like lupus)

The following factors put you at a moderate risk for preeclampsia:

  • First-time pregnancy
  • Pregnancy after age 35
  • Higher body-fat percentage
  • Known family history of preeclampsia in a first-degree relative (parent, sibling)

How is preeclampsia diagnosed?

Preeclampsia is preeclampsia, right? Well, kind of. There are actually two types of preeclampsia, each one with a slightly different set of diagnostic criteria.

Preeclampsia (formerly mild preeclampsia)

Preeclampsia is diagnosed if:

  • Blood pressure is high: Higher than 140 mm Hg (systolic) or 90 mm Hg (diastolic) at least twice, four hours or more apart after 20 weeks of gestation.
  • There's protein in the urine (aka proteinuria): Proteinuria during pregnancy is often indicative of kidney problems. This is no longer needed to diagnose preeclampsia, but if you have it, then it rules you in.

What if you have some of these markers of preeclampsia but not others? "If you have just mildly elevated blood pressure (>140/90), it's gestational hypertension (GHTN)," explains Dr. Conti. "If you have severe range blood pressure (>160/110) and no abnormal labs/no protein, it's severe range GHTN."

Preeclampsia with Severe Features

Preeclampsia with severe features is diagnosed if:

  • Blood pressure is very high: Higher than 160 (systolic) or 110 (diastolic) at least twice, four hours apart (unless you're already on treatment for high blood pressure).
  • There are related conditions: Thrombocytopenia, impaired liver function without other causes, renal insufficiency, pulmonary edema, a new headache (that's unresponsive to medication and not caused by other known issues), and visual disturbances.

Once diagnosed, how is preeclampsia treated?

The ultimate treatment for preeclampsia is delivery of the infant. However, this isn’t always the best option — especially if you’re early in your pregnancy. In this case, managing preeclampsia rather than delivering is the best option.

If you're diagnosed with preeclampsia:

  • You'll be closely monitored at home or at the hospital. If you're staying at home, expect 1-2 visits with your provider a week.
  • Your healthcare provider will check your blood pressure, but you may also be asked to do it at home.
  • You may be asked to keep track of fetal movements.
  • If you're past 37 weeks, your healthcare provider may induce labor (either vaginally or via C-section if needed).

If you're diagnosed with preeclampsia with severe features:

  • You may stay in the hospital for close monitoring.
  • If you're less than 34 weeks along and your condition is stable, you may be able to wait until you're 37 weeks gestation to deliver.
  • If preterm delivery is necessary, you may receive an injection of steroids called betamethasone to help with fetal lung maturity so that the baby has less trouble breathing on their own once born.
  • You will likely receive medications to reduce blood pressure (labetalol, nifedipine, hydralazine) and the risk of seizures (magnesium sulfate).
  • If you're more than 34 weeks along and your condition is stable, your healthcare provider may induce labor.
  • If your condition destabilizes before 34 weeks, your healthcare provider may induce labor.

So once you deliver, are you in the clear?

Not quite, unfortunately. There are some possible long-term effects of developing preeclampsia in pregnancy: The rate of recurrence in subsequent pregnancies is about 14%, and there's also an increased risk of cardiovascular disease later in life. These risks vary based on the severity of preeclampsia. The more severe, the higher the likelihood of developing cardiovascular disease.

Preeclampsia can also be initially diagnosed after delivery. This is known as postpartum preeclampsia. While the medical community isn't certain why this happens, there’s a possibility that preeclampsia may develop anytime in the first six weeks postpartum. Risk factors and symptoms of postpartum preeclampsia are the same as risk factors for preeclampsia.

Can you prevent preeclampsia from happening?

According to ACOG, there's no screening test that can predict preeclampsia. Their recommendation is to identify any risk factors (the ones we listed out earlier) and take steps to address or manage the ones you're able to.

While going to every prenatal care appointment is always important, it's especially important for early diagnosis and proper management. Each appointment gives your provider the opportunity to check your urine, check your blood pressure, and discuss how things are going outside of the doctor’s office. After all, you know your body best and will be able to clue your provider in on any possible early signs of preeclampsia.

If you have high blood pressure and you're thinking about trying to get pregnant, your healthcare provider can help you manage the condition and check in with your heart and kidney function. They can also walk you through what you need to know about preeclampsia and what to look out for (though this article gives you a leg up on that conversation).

Low-dose aspirin may help you reduce your risk for preeclampsia

An aspirin a day isn't just something recommended for folks over the age of 50. ACOG suggests a low-dose aspirin starting in the late first trimester to reduce the risk of preeclampsia for people with one of the high risk factors or two or more of the moderate risk factors we listed earlier.

ACOG advises that a low-dose aspirin regimen begin before 16 weeks of pregnancy, and continue daily until delivery. Talk to your healthcare provider before starting your dose as it's not recommended for all people.

What are other high blood pressure disorders that can occur during pregnancy?

Preeclampsia isn't the only blood pressure condition to be aware of during pregnancy. Here's the lowdown on the others:

  • Chronic hypertension (blood pressure over 140 systolic and/or 90 diastolic) may come before getting pregnant or before the 20th week of pregnancy.
  • Gestational hypertension is high blood pressure (over 140 systolic or 90 diastolic) that's directly associated with your pregnancy. It develops after week 20 of pregnancy but without the lab abnormalities or symptoms of preeclampsia. Some people have severe gestational hypertension, which is above 160 (systolic) and/or 110 (diastolic).
  • Preeclampsia superimposed on chronic hypertension is when a pregnant person already has hypertension, but it's made worse by pregnancy. Symptoms usually show up after 20 weeks.

“We used to think that each of these hypertensive disorders in pregnancy were separate entities, but newer research shows that they are all likely on a spectrum with preeclampsia and so too are the associated risks,” says Dr. Conti. “This is why we take gestational hypertension just as seriously as preeclampsia.”

The type of hypertension you have during pregnancy dictates how it will be treated, but you and the fetus will likely be closely monitored. You may be prescribed blood pressure medication, or develop a treatment plan with a cardiologist and/or a perinatologist (a doctor who specializes in high-risk pregnancies). Your healthcare provider may also recommend other over-the-counter medications or supplements.

What this means for you, right now

Preeclampsia is a serious, life-threatening condition that can affect people both during and immediately following pregnancy. But it can be managed through close monitoring and induced delivery if that's in the best interest of you and your developing fetus.

If you’re considering pregnancy as a part of your future, it's always a good idea to get up to speed on issues encountered during pregnancy like preeclampsia (and Modern Fertility is always here to help you do that). When the time eventually arrives, you’ll be able to more confidently tackle what comes your way — and, importantly, know when you should reach out to your healthcare provider.

This article was medically reviewed by Dr. Jennifer Conti, MD, MS, MSc.

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Chanel Dubofsky

Chanel's writing has appeared in Cosmo, Rewire, Lilith, HelloFlo, & Extra Crispy. She has an MFA in Fiction from Vermont College of Fine Arts & lives in New York. Follow her @chaneldubofsky.

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