Study: Common Pregnancy Complications Could Increase Risk of Heart Disease for Decades

Having one or more complications during pregnancy can increase a person’s risk of developing heart health issues decades after delivery, a new study found.

The research, published earlier this month in The BMJ, followed over 2.1 million Swedish women who gave birth between 1973 and 2015. Those who experienced one of five different complications during pregnancy—gestational diabetes, preeclampsia, preterm birth, hypertensive disorders of pregnancy, or delivering a child small for their gestational age—were more likely to develop ischemic heart disease, also known as coronary artery disease (CAD).

The risk of CAD increased even further if women experienced multiple of these complications. 

“Those increased risks persisted for over 40 years,” Casey Crump, PhD, MD, professor of family medicine at the Icahn School of Medicine at Mount Sinai and study co-author, told Health. “So this showed that these adverse pregnancy outcomes should be considered essentially lifelong risk factors for heart disease in women, which is a really important finding.” 

With an estimated 30% of women expected to experience at least one pregnancy complication, the study could have wide-reaching implications. Here’s what experts had to say about the study’s findings, how pregnancy can affect the heart, and what people should do to stay safe if they’re considering a pregnancy or have been pregnant in the past. 

In Some Cases, a Twofold Increase in Ischemic Heart Disease Risk

The idea that certain pregnancy complications can raise a person’s risk of developing heart disease is not new, but the study adds to the current research by looking at multiple pregnancy complications and teasing out the risks specific to each issue, said Yalda Afshar, MD, PhD, assistant professor in the Maternal Fetal Medicine Department of Obstetrics and Gynecology at the David Geffen School of Medicine, and co-director of the cardio-obstetrics program at UCLA Health. 

For the study, Dr. Crump and his team looked at data from 2,195,266 women who each gave birth to one live child in Sweden between 1973 and 2015. They found that nearly 84,000 of these women had developed ischemic heart disease—the women were an average of 58 years old when they were diagnosed, about 30 years after the median age for childbirth. 

The researchers found that those who’d had certain pregnancy complications years earlier were more likely to develop CAD than others.

In the 10 years after delivery, hypertensive disorders of pregnancy—or when a pregnant person’s blood pressure levels are elevated in some way—were associated with a twofold increase in risk of CAD. Preterm delivery and preeclampsia were associated with a 1.7 and 1.5 times higher risk, respectively. Gestational diabetes and having a small child for their age were the least concerning complications, though they still brought a 1.3-fold and 1.2-fold risk of CAD.

And rates of CAD risk were even higher if a woman had more than one of these pregnancy complications—if a person had three or more of these issues during a pregnancy, the study found that they were at a 2.26-fold increased risk of developing CAD in the 10 years after giving birth.

These rates declined at different rates in the 30 to 46 years after a pregnancy, but they were still slightly elevated as compared to women who never had any of these negative events.

A Push to Learn More About the Relationship Between Pregnancy and the Heart

This study, unfortunately, wasn’t able to assess why these pregnancy complications can lead to issues with the heart, especially so many years after a person gives birth.

Ischemic heart disease, or CAD, is typically caused by plaque buildup in the arteries in the body. This, in turn, makes it challenging for enough blood to flow into the heart and around the rest of the body. Of those women in the study who developed CAD, over 55% had a heart attack and almost 39% had angina, or chest pain, both of which can happen when the heart doesn’t receive enough blood.

Experts still aren’t sure exactly how pregnancy can make this more likely to happen, but they have a few guesses.

“We think that there are likely multiple different underlying causes,” Dr. Crump said. “These adverse pregnancy events can actually trigger new changes in the blood vessels and heart—like inflammation or structural remodeling—that were not present before pregnancy, and that may persist or progress afterward.”

It’s also possible that pregnancy could somehow change the endothelial cells, or those that line the blood vessels in the body, Dr. Afshar added. 

But it could also be that pregnancy is only exacerbating or exposing pre-existing heart issues that could be caused by genetic or other factors, Dr. Crump said. More studies are needed to determine the actual relationship between the two, however.

“As common as preeclampsia and hypertensive diseases of pregnancy are, we don’t understand the biology,” Dr. Afshar told Health. “Unfortunately, women’s health and pregnancy specifically really haven’t been well funded and researched.”

The U.S. needs to invest more in this type of research, she added, especially in light of high rates of maternal mortality and morbidity. In the U.S., mothers are more likely to die during childbirth than in all other high-income countries. This is especially true for Black women, whose maternal mortality rates are almost three times higher than those of white women.

Black women are also more likely to die from heart disease than white women, though it’s not clear how pregnancy complications play a role in those health disparities. Dr. Crump’s study did not look into any potential differences in CAD rates by race.

Avoiding Heart Health Issues Means Pre- and Post-Pregnancy Care

Because these pregnancy complications are so common, the study’s findings illustrate the importance of prioritizing heart health, especially if a person has had a complication during a previous pregnancy.

“Pregnancy truly is a window to your future health,” Dr. Afshar said. “[The study is] actually quite empowering in that it’s low-hanging fruit for actionable items. So if a woman has an adverse pregnancy outcome, there’s a chance to optimize future health.”

The study found that some negative outcomes were more common among women that shared certain characteristics, including being a smoker, having a higher body mass index (BMI), or having a history or diabetes or high blood pressure.

Not every pregnancy is planned, but people with these added risk factors for pregnancy complications can address them with their doctors if they’re considering getting pregnant at some point in the future, Dr. Afshar explained. This and other preconception counseling, she said, could help a woman avoid a pregnancy complication in the first place, and therefore also avoid the increased risk of CAD.

It’s also important to watch for potential heart issues throughout a woman’s life after they’ve had a pregnancy complication, even if it was many years ago.

“This is a call to arms for internists, family medicine docs, cardiologists, etc. to ask about pregnancy complications,” Dr. Afshar said. “Knowing these pregnancy adverse outcomes really can help us start screening postpartum for cardiovascular disease earlier.”

On February 7, the U.S. Preventive Services Task Force (USPSTF) issued a draft statement recommending that everyone who is pregnant be screened for hypertensive disorders of pregnancy. This study supports that idea, Dr. Crump said, but the most important thing is that clinicians are actually adopting it. 

“This is not currently implemented consistently in clinical settings, especially in primary care where most women receive their care,” he said. “It’s really important for clinicians as well as women to recognize that these adverse pregnancy outcomes are long term risk factors for heart disease.”

Plus, pregnancy complications should be tracked, Dr. Crump added. Even if it’s more than 40 years after a person has given birth, their doctor should know that they’re at an elevated risk of developing CAD.

“Understanding these relationships will help us identify high-risk women much earlier in their life, and it will give an opportunity to intervene earlier,” he said. “That’s really our main goal.”