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A leading cause of maternal mortality is something few moms worry about

Experts want greater awareness about this highly treatable condition.

Silhouette of a pregnant African-American woman on a grey background
Getty Images/Darya Komarova
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Keren Landman is a senior reporter covering public health, emerging infectious diseases, the health workforce, and health justice at Vox. Keren is trained as a physician, researcher, and epidemiologist and has served as a disease detective at the US Centers for Disease Control and Prevention.

Crystal Jackson, who lives in Fort Pierce, Florida, had never even heard of preeclampsia when it nearly took her life.

Thirty-three weeks into her first pregnancy, Jackson suddenly developed a terrible headache and severe nausea. Her then-boyfriend took her to a drugstore, where she put her arm in a machine to check her blood pressure: “It was sky high,” she said. She went straight to the hospital, where providers diagnosed her with preeclampsia — a life-threatening condition associated with pregnancy whose first signs include high blood pressure. Just a few hours later, she delivered a healthy but premature baby girl by emergency cesarean section.

She was a college student at the time, and a future nurse — but the risk of a pregnancy-associated blood pressure disorder “never even crossed my radar” until it happened, Jackson said.

She’s not alone: About one-third of maternal deaths are caused by medical problems related to high blood pressure, also called hypertension — a condition that is in many cases preventable.

But hypertension isn’t typically associated with people of childbearing age. “We often think of it as something that happens to our grandpas,” said Laney Poye, who directs communications and engagement at the Preeclampsia Foundation, a non-profit organization that advocates for improving outcomes of hypertensive disorders of pregnancy.

“We don’t think about it as something that’s going to happen to a young woman,” she said. “We don’t think about it in terms of why it’s so dangerous for a pregnant person.”

That’s a big problem. Maternal mortality is at crisis levels in the US: In 2021, for every 100,000 babies born in the US, 33 women died — and indigenous and Black women are two to three times more likely to die of a pregnancy-related condition than white women. At the same time, the hypertension disorders that so often cause these deaths are increasingly common in the US: A 2022 study found hypertension complicated twice as many millennial and Gen Z-er pregnancies as it did baby boomer pregnancies.

However, experts say a lack of knowledge about one of the most important causes of those deaths, both among patients and providers, keeps us from preventing many of them.

Here’s what everyone needs to know.

Different types of pregnancy-related hypertension have different causes

Hypertension that affects a pregnancy can start before, during, or after a person becomes pregnant, and it comes in a few different flavors that are associated with different processes taking place in the body.

Preeclampsia is the most concerning type of pregnancy-related hypertension, and affects about 4 percent of US pregnancies. In this disorder, a pregnant person has above-normal blood pressure — where the first number is at least 140 and the second number is at least 90 — but also, signs that the high blood pressure is damaging other organs. (One of the first organs to show signs of wear are the kidneys; the condition usually gets diagnosed when a provider finds protein in the urine of a pregnant person with high blood pressure.)

Experts believe that preeclampsia is caused by problems with the placenta, a temporary organ that grows alongside the fetus inside the womb during pregnancy and provides it with oxygen and nutrients filtered from the parent’s blood. When blood vessels in the womb don’t grow exactly the right way, that leads the placenta to signal that it’s not getting enough blood flow. In response, the pregnant person’s body raises the blood pressure to try to better perfuse the organs. But in preeclampsia, the feedback loop never gets completed — even with an increase in blood pressure, the placenta just keeps signaling that it’s thirsty.

A daily aspirin helps prevent preeclampsia in people who are at high risk for developing it, although it’s often underprescribed. Once a pregnant person develops preeclampsia, the condition can’t be reversed with medications. Only delivering the baby — and the placenta — reverses the process, and even then, does not always completely solve things. In up to 28 percent of cases, preeclampsia persists or worsens after delivery.

The outcomes of this kind of pregnancy-related hypertension are the most severe: About 16 percent of maternal deaths in high-income countries are caused by preeclampsia.

Preeclampsia is an important threat to maternal health, but it isn’t the only type of pregnancy-related hypertension that exists. High blood pressure can happen before or during pregnancy without damaging the kidneys and other organs, and it’s a risk factor for poor fetal growth and preterm birth.

These kinds of hypertension, categorized as chronic or gestational hypertension, don’t have the same causes as preeclampsia — that is, they don’t start with the placenta. However, 25 to 35 percent of people with these conditions go on to develop preeclampsia.

But that risk is not inevitable: In one study, pregnant women whose chronic hypertension was well-controlled during pregnancy were more than four times less likely than untreated women to develop preeclampsia.

Chronic hypertension is on the rise, and has doubled over the past decade, now affecting 13 to 30 percent of women of reproductive age. That makes it important not only to diagnose hypertension early in pregnant people, but also to diagnose and treat it in women who could get pregnant, before they do.

Pregnancy-related hypertension isn’t getting diagnosed or treated early enough, in part because people don’t see it as a big risk

All too often, the early diagnosis of hypertension, either before or during pregnancy, doesn’t happen in time to prevent it from causing harm. Why is that?

There’s historically been a lot of disagreement among medical professional societies about what constituted hypertension in pregnancy — and whether lowering elevated blood pressures in pregnancy would harm the fetus. Only last year did the American College of Obstetricians and Gynecologists expand its definition to include a greater number of pregnancies (and comport with most other societies’ guidelines).

The resulting confusion wasn’t helped by the fact that on a global scale, there’s little shared cultural understanding of what pre-pregnancy care should look like — that is, the care prospective parents get before they even conceive, which could include screening for blood pressure, diabetes, smoking, and other risks. “I don’t think we have a great public perception of what preconception care is,” said Natalie Cameron, a physician at Northwestern University’s medical school who studies pregnancy-related cardiovascular health. “If we don’t optimize medical conditions before pregnancy, it can really have adverse effects for the mom and the baby.”

But in a nation where nearly half of all pregnancies are unplanned, many people who will soon become pregnant may not think of themselves as needing to get preconception care. Access to care also plays a role: The barriers to getting preconception care track with the barriers to getting maternal care — and with risk factors for maternal death. People with low incomes, who live in rural regions, and who aren’t white are less likely to get this type of care.

Compounding that is a public perception of hypertension as something that’s a low-grade, chronic problem that’s easily treatable with medication. Although that might be true for many people, pregnancy really amplifies hypertension’s risk — but many people don’t understand that, said Poye. Often, when pregnant women hear they have high blood pressure, “They think, ‘Oh, okay, it’s not a really big deal. They’ll just give me some medicine and I’ll continue on and then we’ll deliver this baby,’” she said.

But in reality, once someone’s on the path to preeclampsia, there’s no turning back until delivery.

Even then, there’s limited understanding of the risk hypertension poses in the post-delivery period, both by providers and patients. More than 60 percent of maternal deaths due to preeclampsia actually happen after delivery, usually during the first six weeks after birth. Additionally, people who have new-onset hypertension during pregnancy are more likely to live with hypertension for years afterward. “That sort of takes women by surprise,” said Poye.

It also surprises some providers. Delivery used to be thought of as the cure for preeclampsia, but while the science now clearly shows that’s not the case, many health care providers still don’t fully grasp how much risk pregnancy-related hypertension poses even after delivery. More than three-quarters of primary care providers who ask female patients about pregnancy history don’t ask if they had preeclampsia — even if they ask about diabetes or smoking.

When providers aren’t fully aware of the risk, they might not react with the appropriate level of concern to a patient’s complaint about, for example, postpartum headache or leg swelling. Over years of working with preeclampsia survivors, said Poye, “there are almost always signs and symptoms that have occurred, things that are making the patient feel uneasy. And so often she’s just unheard by her providers.”

Racial inequities in diagnosis and treatment are rooted in older, structural inequities

In the US, women of color are more likely to have serious medical complaints go unheard and to otherwise be mistreated during and after pregnancy. That’s part of what makes them more likely to have a hypertension-related complication go undetected until it becomes a crisis.

However, women of color also encounter other inequities earlier in the process, much of it rooted in historical and structural racism. Differences in access to healthy foods and physical activity opportunities underpin higher rates of obesity in women of color — an important risk factor for hypertension. And there are other inequities: Women of color are more likely to face barriers to accessing care before and after conception, often due to lower income and education levels, and hypertension in pregnant Black women in particular is less likely to be controlled.

“There is historical mistrust in the health care system, which also affects how women will interact with their doctors and how doctors, in turn, can interact with them, even if it’s just on an implicit level,” said Cameron.

Progress is possible

There’s a lot of room to improve hypertension care during pregnancy, said Poye: “At the end of the day, we know what to do.”

The US Preventive Services Task Force recently drafted new blood pressure screening recommendations for pregnant women. And at the state level, Perinatal Quality Collaboratives — networks of hospitals, health departments, professional societies, insurers, and others — are working to improve care at the local level.

But it’s also important to raise awareness among the people most likely to be pregnant, said Crystal Jackson, who has now survived four pregnancies complicated by preeclampsia, and works with pregnant women both as a nurse and volunteer.

“The main thing right now, I think, from the ground up, is just awareness,” Jackson said. “A lot of women, especially young or first-time moms, they’re really not thinking about the what-ifs — they’re not thinking about complications that could arise.”

“It’s an afterthought — until it’s not,” she said.