Having a baby has been associated with a slightly protective effect against breast cancer, however, a recent study is showing this benefit may take as long as 20 years to kick in.
The study looked at data from 15 previous studies on women under the age of 55.
Researchers found that in comparison with women of the same age who had never had a baby, the women who had given birth had an increased risk for breast cancer that peaked approximately five years later.
They also found that this increased risk lasted for about 24 years.
The increased breast cancer risk was stronger in women who were older when bearing their first child, or if they had a strong family history of breast cancer. Women who had pregnancies at a younger age, did not show the same increased risk.
Halle Moore, M.D., of Cleveland Clinic, did not take part in the study, but said breast cancer is still most common in women after menopause.
“It’s important to remember that the actual number of breast cancers that occurred in this population was very low and that the increase in risk is actually a fraction of a percent if you look at the actual numbers of cancers,” said Dr. Moore.
Dr. Moore said that women – regardless of whether they’ve given birth – should pay attention to any changes in their body and talk to their doctor.
“For all women, who may be at risk for breast cancer, I think it’s important to be aware of any changes in the breast and report those to your doctor,” she said.
Dr. Moore said even though this study showed an elevated risk following pregnancy, breast cancer is still less common in younger women.
Complete results of the study can be found in Annals of Internal Medicine.