| Health / Health News |
Breast cancer protection from pregnancy starts decades later
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.
Breast cancer protection from pregnancy may not begin until as many as 30 years after the last pregnancy. Image credit: NIEHS
Scientists 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 suggest breast cancer protection from pregnancy may not begin until as many as 30 years after the birth of the last child.
"We were surprised to find that an increase in breast cancer risk lasted for an average of 24 years before childbirth became protective," said Dale Sandler, Ph.D., head of the Epidemiology Branch at the National Institute of Environmental Health Sciences (NIEHS), part of NIH. "Before this study, most researchers believed that any increase in risk lasted less than 10 years."
The scientists also found that the association between recent childbirth and breast cancer risk was stronger for women who were older at first birth, had more births, or had a family history of breast cancer.
Breastfeeding did not appear to have any protective effect, even though it is generally thought to reduce breast cancer risk. Many of these additional factors were not addressed in earlier studies, underscoring the statistical power of this larger project.
Childbirth is an example of a risk factor that is different for younger women than older women.
This difference is important because it suggests that we may need to develop tools for predicting breast cancer risk that are specific to young women. (National Institutes of Health)
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