IRP scientists find that breast cancer protection from pregnancy starts decades later
Breast cancer risk remains elevated 20-30 years after childbirth
In general, women who have had children have a lower risk of breast cancer compared to women who have never given birth. However, new research has found that moms don’t experience this breast cancer protection until many years later and may face elevated risk for more than 20 years after their last pregnancy.
Scientists at the National Institutes of Health, along with members of the international Premenopausal Breast Cancer Collaborative Group, found breast cancer risk increases in the years after a birth, with the highest risk of developing the disease about five years later. The findings, which appeared online in the Annals of Internal Medicine, suggest breast cancer protection from pregnancy may not begin until as many as 30 years after the birth of the last child.
According to senior author Dale Sandler, Ph.D., head of the Epidemiology Branch at the National Institute of Environmental Health Sciences (NIEHS), part of NIH, a few prior studies reported an increase in breast cancer risk after childbirth. However, most of what researchers knew about breast cancer risk factors came from studies of women who have gone through menopause. Since breast cancer is relatively uncommon in younger women, it is more difficult to study.
This page was last updated on Friday, January 21, 2022