A new study has found a link between births, breastfeeding and breast cancer that may provide insight into why African-American women have higher rates of a more aggressive form of the disease.

The study, published Tuesday in Cancer Epidemiology, Biomarkers and Prevention, showed that women who gave birth to two or more children had a 50% overall increase in a particularly aggressive form of breast cancer called estrogen or progesterone receptor-negative breast cancer.  The same increase was not found when the women had breastfed.

While breast cancer occurs more frequently in white women, African-American women are more likely to die from the disease because they often develop more aggressive breast cancers, according to the American Cancer Society.

According to the authors of the study, there is a link between more births and developing estrogen or progesterone receptor-negative breast cancer, therefore, “because African-American women have had more births on average than U.S. white women, this association may” explain the higher rates of the cancer among African-American women.

The authors suggest that encouraging African-American women to breastfeed may help reduce the rate of aggressive types of cancers that disproportionately affect them.

The data used in the study was collected from the Black Women’s Health Study, which began in 1995 and follows 59,000 African American women who provide detailed health information to the study every two years.

To learn more about African-American women and breast cancer, click here.

(Photo: Fort Worth Star-Telegram/MCT/Landov)