New Haven, Conn. — Hypertensive disorders in pregnancy (HDP) — like chronic or gestational hypertension, preeclampsia, and eclampsia — are among the leading causes of maternal and infant death in the United States.

Between 2017 to 2019, 16% of all U.S. pregnancies were complicated by an HDP diagnosis, with much higher rates seen among non-Hispanic Black/African American and American Indian/Alaskan Native women. But HDPs don’t just affect women in the short term; these disorders can increase their long-term risk for heart disease, kidney disease, and stroke.

But there could be an opportunity to mitigate these longer-term health risks through breastfeeding, Yale researchers have found. In a new study, they discovered that an HDP diagnosis before or during pregnancy related to higher odds of never breastfeeding, or for those who initiated breastfeeding, higher probability of stopping. The findings suggest women with HDPs may benefit from targeted interventions that promote their exposure to the cardioprotective benefits of breastfeeding.

The findings are published in the journal JAMA Network Open.

“We looked at breastfeeding initiation, or whether you ever started breastfeeding,” said Deanna Nardella, an instructor of pediatrics and physician-scientist with Yale School of Medicine (YSM) and first author of the study. “We also looked at breastfeeding duration. So, if you did start, how long did you breastfeed for? Having a hypertensive disorder of pregnancy was associated with worse outcomes for both of these measures.”

There can be many barriers to starting, and sustaining, breastfeeding after childbirth, from facing lactation challenges and inadequate parental leave policies to lack of breastfeeding education among patients and healthcare providers alike. In the U.S., 83% of women start breastfeeding, according to the Centers for Disease Control and Prevention, but only 25% continue to exclusively breastfeed through the first six months — the recommended duration by leading health organizations.

“These statistics beg the question, why is that the case?,” Nardella said. “As a practicing pediatrician in the New Haven community, it is not often I see parents who truly do not want to breastfeed. Rather, I frequently see parents try to breastfeed, shortly thereafter encountering common — and often addressable — challenges, such as pain, latch difficulties, and milk supply concerns.

“Unfortunately, many families do not get the timely care they need to address such challenges, resulting in breastfeeding cessation. I believe that the attrition we see in U.S. breastfeeding rates, particularly within the early weeks to months postpartum, in large part reflect systems level issues.”

Other maternal comorbidities, including chronic and gestational diabetes, have been shown to negatively influence breastfeeding outcomes, but little is known about the breastfeeding outcomes for those with HDP despite its high prevalence among pregnant people in the United States. For Nardella, understanding this relationship is critical to promoting health equity.

“We know that Black and Native women in the U.S. have higher rates of hypertensive disorders of pregnancy,” she said. “These communities also have the lowest breastfeeding rates. Though we cannot say that HDPs directly cause these observed inequities, understanding the mechanisms of the relationship between HDP and breastfeeding initiation and duration could promote more equitable long term cardiometabolic outcomes for pregnant individuals and infants from these communities.”

For the new study, researchers sought to better understand this relationship by analyzing data from the Centers for Disease Control and Prevention (CDC) Pregnancy Risk Assessment Monitoring System (PRAMS). PRAMS surveys women across the U.S., usually around four months postpartum, on their attitudes, beliefs, and experiences during their pregnancy, prenatal, and postpartum periods.

Their sample included women who had delivered a live infant between January 2016 and November 2021 and who had provided complete data for HDP and non-initiation or cessation of breastfeeding. The researchers defined HDP as self-reported high blood pressure or hypertension, preeclampsia, or eclampsia before or during pregnancy. Women were determined to have never breastfed if they reported “no” to ever breastfeeding on the survey. Among those who reported breastfeeding, researchers defined time to cessation as 0.5 weeks if they reported breastfeeding less than one week, their exact breastfeeding duration (in weeks) if provided, or infant age at the time of survey completion (in weeks) if they reported they were still breastfeeding.

Their analytic sample included 205,247 participants — a weighted sample representing nearly 11 million U.S. women — from 43 states, Washington, D.C., and Puerto Rico, and across all socioeconomic, racial, and ethnic backgrounds. They found that women with an HDP had 11% higher odds of never breastfeeding and, among those who did start breastfeeding, a 17% higher probability of stopping at some point during the postpartum period. The median time for breastfeeding cessation was 17 weeks shorter for women with HDP than those without HDP. These findings suggest a negative association between HDP and breastfeeding outcomes.

“Over 80% of U.S. families choose to breastfeed their infant,” said Sarah Taylor, professor of pediatrics (neonatal-perinatal medicine) at YSM and co-author of the study. "However, most do not reach the goal, set by the American Academy of Pediatrics, to exclusively do breastfeeding for six months. Research, such as this study showing an association between HDPs and shorter breastfeeding duration, guides the development of strategies to help all families reach their breastfeeding goal.”

Future studies to identify the mechanisms that underlie this relationship between HDP and breastfeeding are required to develop targeted, innovative strategies to improve breastfeeding outcomes for people with HDP, researchers said.

“Such strategies could include having a standard, dedicated prenatal lactation consultation for those individuals who wish to try breastfeeding and have risk factors for experiencing worse breastfeeding outcomes, such as HDP,” Nardella said. “Pregnancy is a critical, and often underutilized, period for lactation education and support.”

She added: “This paper provides foundational knowledge on which to build future studies to understand how our health systems can best support those individuals with hypertension in reaching their personal infant feeding goals. As a system, we must do better about supporting women with HDP in reaching whatever their infant feeding goal may be, particularly if it involves any amount of breastfeeding. Such support could promise long term improvements in health outcomes for many pregnant individuals and their infants, especially among communities with high risk of cardiometabolic disease and breastfeeding cessation.”

The study was supported by grants from the Yale Pediatric Scholars Program, the Yale National Clinician Scholars Program, and the Clinical and Translational Science Awards from the National Center for Advancing Translational Science, part of the National Institutes of Health (NIH).