Poor women and women who didn’t finish high school are more likely to be hospitalized for heart failure, even when trying to lead otherwise healthy lives, according to a study published in the Journal of the American College of Cardiology and reported by Reuters Health.

For the study, researchers looked at data from the Women’s Health Initiative, which was funded by the U.S. National Institutes of Health. The study included about 26,000 healthy, post-menopausal women who were surveyed every six months for eight years on health and lifestyle habits, income and education levels. The study focused on those who were hospitalized for heart failure.

Researchers found that for women with household incomes of less than $20,000 per year, 57 out of 10,000 women, on average, were hospitalized for heart failure. However, for women with household incomes of more than $50,000, that number dropped to 17 out of 10,000.

Moreover, when the researchers accounted for race, underlying health factors and whether the women smoked and drank, they found that women in the lowest income bracket still had a 56 percent higher risk of heart failure than the wealthiest women. And women who didn’t finish high school were 21 percent more likely to be hospitalized than college grads.

Researchers believe that several factors might lie behind the disparity. For instance: Poor women have less access to preventative care; they communicate less with doctors; and they have a poorer understanding of health risks. The quality of a woman’s neighborhood—for example, do nearby grocery stores sell healthy food, and is it safe to walk outside—could also influence her heart health.