Over two recent decades, there was a significant increase in the prevalence of maternal cardiovascular (CV) comorbidities and disease (CVD) and postpartum pregnancy-related CV complications, according to a multi-institutional study.

The findings, drawn from 56,833 pregnancies in 38,996 individuals from 2001 to 2019, found CV complications in 15% of mothers with or without established CVD. The complications highlight pregnancy as a crucial life opportunity for CV health optimization, said investigators led by Emily S. Lau, MD, MPH, cardiologist at Massachusetts General Hospital in Boston, writing in Circulation.

Contemporary trends toward older maternal age, obesity, and diabetes appeared to play a role. Pregnancy-related CV complications were most common among women older than 40 years. Obesity, as well as diabetes and hypertension, was significantly more prevalent among those who experienced pregnancy-related CV complications, Lau told Medscape Medical News.

The mean cohort age at the start of pregnancy was 32 ± 5 years, and participants were stratified by maternal age at the time of delivery (< 25, 26-35, 36-45, and > 45 years). The overall prevalence of maternal CVD was 4% (age-adjusted to 8%) and increased over 19 years, with an age-adjusted prevalence of 1% in 2001 and 7% in 2019 (P < .001). CV complications emerged in 8280 pregnancies.

The 15% incidence of complications (age-adjusted to 17%) increased over the 1-year follow-up period, with an age-adjusted incidence of 11% in 2001 and 13% in 2019 (P < .001). CV complications within a year postpartum were more frequent in individuals with a greater burden of maternal CVD and CV comorbidities (diabetes, 6% vs 3%; hypertension, 23% vs 5%; and CVD, 10% vs 3%; P < .001 for all).

The US has the highest maternal mortality rate among industrialized countries, with an estimated rate of 32.9 deaths/100,000 live births in 2021.

“Many CV risk factors can and should be addressed in primary care or ob/gyn settings, with referral to cardiologists reserved for patients with overt CV disease or higher-risk profiles,” Lau said. “However, as women are entering pregnancy with more CV comorbidities and disease, we will need to think about more innovative integrated care models.”

A Natural Stress Test

Pregnancy is a kind of natural cardiac stress test. “That’s because a normal pregnancy imposes major hemodynamic, hormonal, and metabolic demands on the mom,” Lau said. Blood volume rises by 40%-50%, increasing cardiac output, and systemic vascular resistance falls, leading to increased heart rate and stroke volume in order to maintain perfusion.

“And finally, delivery and the immediate postpartum period are accompanied by abrupt shifts in volume and pressure that can unmask previously compensated cardiovascular disease,” she said.

However, most women without a known CVD diagnosis do not undergo rigorous CV screening or assessment as part of routine prenatal care. “So, our study emphasizes that we need to think of ways of better integrating CVD prevention into prenatal care, given the growing burden of prepregnancy cardiometabolic and CVD,” Lau said. 

Commenting on the study but not involved in it, Jennifer Lewey, MD, MPH, director of the Penn Women’s Cardiovascular Health Program at the University of Pennsylvania in Philadelphia, found the age factor significant. “What was striking was that women over age 40 had higher rates of CV risk factors and disease and complications. I expect that as the age at delivery increases, we will be taking care of more pregnant women with CV issues.”

As testimony to the problem, the European Society of Cardiology recently released guidelines on managing CVD in pregnancy. Lewey said women of reproductive age need greater access to CV screening, testing, and preconception risk and safety counseling to get at-risk patients the necessary treatment.

While most risk factors can be safely managed in primary care or by obstetricians and maternal-fetal medicine practitioners, “patients with unresolved problems such as uncontrolled hypertension or established CV disease need consultation with a cardiologist who specializes in pregnant populations.”

In an accompanying editorial, cardiologist/epidemiologist Sadiya S. Khan, MD, MSc, and maternal-fetal medicine specialist Stephanie A. Fisher, MD, MPH, of Northwestern University Feinberg School of Medicine in Chicago, commended the authors for assembling such a large pregnancy cohort and for their innovative use of validated machine-learning methods to leverage unstructured clinical note data.

They noted that in the approximately 3.5 million US women who were pregnant in 2023, the pregnancy-related mortality ratio (death related to or aggravated by the pregnancy during or within a year postpartum) was 18.7 per 100,000 births and had increased from 2001. Nearly half of the deaths were attributed to CV morbidity, including cardiomyopathy, stroke, and hypertensive disorders of pregnancy.

Studies such as that of Lau and colleagues offer key opportunities for future observational analyses, the editorial commentators wrote. “This study also underscores the need to standardize definitions of pregnancy key outcomes, such as pregnancy-related cardiovascular complications. Currently, studies vary in how CVD is defined in pregnancy, and this can make it challenging to compare event rates across studies and assess trends over time.”

The analysis also highlights key unanswered questions for future clinical trials, such as recommendations for preventing CVD before, during, and after pregnancy, they added.

“The present study is a welcome addition to the literature at the intersection of reproductive and cardiovascular epidemiology,” Khan and Fisher concluded. “Integrating prenatal care with CVD preventive care has the potential to bend the curve in maternal mortality.”

Lau’s research was reported to be supported by grants from the National Institutes of Health, the American Heart Association, and the Massachusetts Life Sciences Center. Several coauthors reported similar research support. Lau disclosed consulting or advisory board service with Roon, Systole Health, and Amissa Health, unrelated to this work. Co-author Patrick T. Ellinor reported sponsored research support from Bayer AG and IBM Health and also served on advisory boards or consulted for Bayer AG, Quest Diagnostics, MyoKardia, and Novartis. Lewey reported having no conflicts of interest. Khan reported receiving research support from the National Heart Lung, and Blood Institute and the American Heart Association.