Boston, MA -- Previous studies have shown preterm delivery to be associated with an increased risk of cardiovascular disease, but it is unknown whether this risk remains after adjusting for a woman's pre-pregnancy lifestyle and risk factors of CVD. In a new study led by Brigham and Women's Hospital, investigators have found that women who have delivered prematurely before 37 weeks have a 40 percent increased risk of developing cardiovascular disease when compared to women who delivered their babies after 37 weeks. Women who delivered earlier, before 32 weeks, had double the risk of CVD.
The research was published in Circulation on February 2, 2017 in the American Heart Association's "Go Red for Women" issue.
"Delivering a preterm infant may be an early warning signal of high risk for cardiovascular disease", says Lauren Tanz, MSPH, first author and a Programmer and Analyst at BWH and a doctoral student at the Harvard T.H. Chan School of Public Health. "Since cardiovascular risk develops over a lifetime, it's not too early for these women to adopt a heart healthy lifestyle."
Researchers reviewed data on 70,182 women in the Nurses' Health study II and examined the association between premature delivery and cardiovascular disease. After adjusting for age, race, parental education, and pre-pregnancy lifestyle and CVD risk factors, the team found that preterm delivery was associated with an increased risk of CVD when compared to women who gave birth at term. Risks were stronger for women who delivered more than one preterm infant. The heightened risk of CVD was true even after preterm deliveries that were not complicated by hypertensive disorders of pregnancy.
While 31 percent of women will die from CVD, that figure rises to 36 percent for those who deliver 3-7 weeks early and up to 60 percent for women who deliver 8 or more weeks before term. Researchers are hopeful that this finding will help identify women who should be especially concerned about a later risk of developing CVD.
"Very little of the risk associated with preterm delivery was explained by traditional cardiovascular risk factors like overweight and hypertension. We need more research to understand why women who deliver preterm are at higher risk, and what we can do to help them lower it," says Janet Rich-Edwards, ScD, senior author of the research and director of Developmental Epidemiology at the Connors Center for Women's Health and Gender Biology at BWH.
The study was funded by the following grants: National Heart, Lung, and Blood Institute 1F31HL131222-01 6, NIH 5T32HL098048-05 7, NIH 5T32HL098048-04 8, NIH UM1 CA176726 9 and the National Heart, Lung, and Blood Institute HL088521 10. This work was also supported by awards from the American Heart Association (12PRE9110014, 11 13GRNT17070022).
Brigham and Women's Hospital (BWH) is a 793-bed nonprofit teaching affiliate of Harvard Medical School and a founding member of Partners HealthCare. BWH has more than 4.2 million annual patient visits and nearly 46,000 inpatient stays, is the largest birthing center in Massachusetts and employs nearly 16,000 people. The Brigham's medical preeminence dates back to 1832, and today that rich history in clinical care is coupled with its national leadership in patient care, quality improvement and patient safety initiatives, and its dedication to research, innovation, community engagement and educating and training the next generation of health care professionals. Through investigation and discovery conducted at its Brigham Research Institute (BRI), BWH is an international leader in basic, clinical and translational research on human diseases, more than 3,000 researchers, including physician-investigators and renowned biomedical scientists and faculty supported by nearly $666 million in funding. For the last 25 years, BWH ranked second in research funding from the National Institutes of Health (NIH) among independent hospitals. BWH is also home to major landmark epidemiologic population studies, including the Nurses' and Physicians' Health Studies and the Women's Health Initiative as well as the TIMI Study Group, one of the premier cardiovascular clinical trials groups. For more information, resources and to follow us on social media, please visit BWH's online newsroom.