Parents who have five or more children may face a higher risk of heart disease than those who have only one or two keiki, according to new findings from public health researchers at the University of Hawaiʻi at Mānoa.

 Researchers led by Sara Hipp, a recent graduate of the Master of Public Health (MPH) program, looked at data from nearly 25,000 participants ages 50 and older who took part in a national health survey.

 "Many studies have linked women's reproductive characteristics, such as their age at their first childbirth, with their risk of heart disease later in life," Hipp said. "But there wasn't much known about the association between family size and heart disease, and very few studies have looked at how fatherhood may relate to men's risk of heart disease."

 Hipp and her co-authors found that 30 percent of the parents who said they had five or more children had a heart condition, such as coronary heart disease, angina, or congestive heart failure. Just 22 percent of those who had only one or two children, and 21 percent of those who had no children said they had been diagnosed with a heart condition. Among all the respondents, about one quarter said they’d been told by a doctor within the past two years that they had heart disease.

 "Our data showed that in both sexes, having more children was associated with a greater risk of heart disease," Hipp said. The link remained even when the researchers adjusted for other characteristics that can affect people's risk of heart disease, such as their age, race/ethnicity, and birthplace. And in women, the association persisted even after the researchers adjusted for lifestyle variables, such as whether they smoked or exercised at least twice a week.

 "This work is important because it presents sophisticated analyses in a very large sample that not only replicates findings from a number of smaller studies, it also expands this body of work to look at the relationship between parenthood and heart disease in men," said Yan Yan Wu, PhD, an assistant professor of biostatistics with UH Public Health.

 Among women, 31 percent of those who gave birth to five or more children reported heart disease, compared with 21.0 percent of those who had one or two children, and 21 percent of those who did not have children. Among men, 29 percent of those who had fathered five or more children reported heart disease, compared with 24 percent of those with one or two children, and 21 percent of those without children.  

 The three key risk factors for heart disease are high blood pressure, high cholesterol, and smoking, and about half of U.S. adults have at least one of these risk factors, the researchers noted.

 "Implementing more supportive policies in the U.S. could help to address the health disparities that we see between larger and smaller families," Hipp said.

 The new findings are published in the Journal of Aging and Health. Hipp and Wu's co-authors also included UH researcher Nicole Rosendaal, MS, and Catherine Pirkle, PhD, an assistant professor with UH Public Health.