It's normal for expectant parents to worry about how well their baby is developing and growing. But could a newborn's birthweight serve as a red flag for risks to mom's future health, too? A new study, presented at the American College of Cardiology's Annual Scientific Session Together with World Congress of Cardiology (ACC.20/WCC), suggests that giving birth to a baby under 5.5 pounds may be an independent risk factor for developing changes in heart function that can lead to heart failure, a condition in which the heart is unable to pump enough blood and oxygen to meet the body's needs.
Recent data suggest adverse pregnancy outcomes, such as preeclampsia, high blood pressure during pregnancy, pre-term birth (<37 weeks) and low birth rate, are on the rise. In fact, 1 out of every 3 women in this study reported one of these issues. Echocardiograms--a test showing pictures of the heart and how well it is pumping--in these women were more likely to show abnormal changes in the heart compared with women who did not experience complications. These changes often represent early signs of heart failure risk.
Researchers said their findings are the first to examine early changes in heart function prior to a woman developing symptomatic heart failure and should raise concerns about the cardiovascular impact of adverse pregnancy complications.
There is emerging evidence that what happens during pregnancy may be a window into a woman's future cardiovascular health, but there are still important knowledge gaps about the early trajectory following pregnancy complications and structural changes that happen before someone has an event, which may ultimately help us to identify targets for prevention. At 30 years of follow up, the women who had an adverse pregnancy outcome in our study had a lower absolute global longitudinal strain on their echocardiograms, which is an early marker of increased risk for heart failure. Clearly, the risk for heart disease doesn't go away when pregnancy ends, and these complications are a critical piece of a woman's past medical history that is not always routinely reported or asked about."
Priya Mehta, MD, cardiology fellow at Northwestern University in Chicago and the study's lead author
The study included 936 women from the Coronary Artery Risk Development in Young Adults (CARDIA) Study, a national, longitudinal cohort study that has followed people from a young age to examine the development of, and risk factors for, cardiovascular disease. Mehta said that, unlike previous studies that focused on a first or specific pregnancy, their study included women who had been followed for three decades after recruitment in 1985-86 and, therefore, was able to capture the woman's entire reproductive life course. Participants were 24 years old, on average, at the start of the study, and about half were black. Women who already had diabetes, high blood pressure or heart failure were excluded. Researchers collected and analyzed the number of pregnancies, pregnancy complications (preeclampsia, gestational hypertension, pre-term birth of <37 weeks gestation and birthweight <5.5 pounds), cardiovascular risk factors and findings on their echocardiogram at a 30-year follow-up. Mehta and the team looked specifically at changes in global longitudinal strain, which is a well-validated marker of the heart not pumping well and can predispose someone to heart failure.
Of the women in the study, 330 (35%) reported at least one adverse pregnancy outcome over an average of two births during the study period. At their 30-year follow-up, women who had experienced an adverse pregnancy outcome had a nearly 1% lower (worse) absolute global longitudinal strain--a magnitude of difference that has been shown in other studies to be associated with an increased risk for incident heart failure.
After adjusting for other known risk factors for heart disease, only low birthweight remained significantly associated with echocardiogram changes suggestive of increased risk for heart failure. For women with hypertensive disorders of pregnancy (preeclampsia or gestational hypertension) or pre-term birth, the risk for heart failure seemed to be explained, in part, by higher rates of high blood pressure, diabetes and obesity that developed in these women. Although more research is needed, Mehta said the findings underscore the need to be more intensive about managing the cardiovascular risks seen with these adverse pregnancy outcomes.
"Women who experience adverse pregnancy outcomes have more risk factors for heart disease at younger ages and, ultimately, have a higher rate of [early] heart disease," Mehta said. "Even though pregnancy complications have been included in some cardiovascular disease prevention recommendations and are named as a risk enhancer in the ACC/AHA primary prevention guideline, there needs to be more intensive surveillance and screening. We are missing women at high cardiovascular risk if we don't make it routine practice to take adverse pregnancy outcomes into account when we inquire about patients' cardiovascular history."
The other challenge, she said, is that clinicians must try to engage women at a time when they are focusing their energy on motherhood and their newborn, rather than remembering to prioritize self-care.
This study is limited by its reliance on self-reported information about pregnancy history; future studies should validate with medical records and determine whether an echocardiogram could help identify women who need strategies to lower heart risks.
Mehta plans to extend this research by exploring the mechanisms that lead to these women developing heart disease in order to identify strategies for prevention before, during and after pregnancy. Her future research will be supported through the ACC/Merck Research Fellowship Award, as one of two national recipients starting in July 2020.
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