Study: Breast Cancer risk increases after giving birth, lasts for decades

According to new research out this week, women who have babies have an increased risk for breast cancer, compared to women who don't give birth. 

The study from the University of North Carolina reports that the risk rises and then falls over time, peaking about five years after birth. 

Allina Health Surgical Oncologist Dr. Annie Callahan says the changes in risk are small. 

“This certainly should not be used to make any decisions about childbirth or timing of childbirth because that's an intensely personal decision that is made by everybody at their own time, and breast cancer risk shouldn't ever be something that fits into that,” Callahan said. 

The increased risk has to do with estrogen receptors, proteins found inside cells.

“We don't completely understand what causes it. I don't think that this should change anything in how people are screened, but if it helps to increase the awareness and increase the thinking about that possibility, then it's done some good,” Callahan said.  

According to the study, which only examined women younger than 55, the higher risk lasts for 24 years after having a baby. It then switches to a lower risk until reaching the lowest point after 24 years. 

“If a woman who has recently had a baby has a mass in their breast or a finding in their breast that doesn't go away, even though they may still be breastfeeding, or there still might be changes in their breast, they should have that evaluated and not assume it's just due to breastfeeding,” Callahan said. 

The study’s conclusion says that health care providers should consider recent childbirth a risk factor for breast cancer in young women.

The risks were greater for women who were older at first birth or who had more births. The American Cancer Society recommends women with average risk begin annual mammograms at age 40.