Findings of a new research have shown that mothers may have higher risk of developing breast cancer compared with women who never had children.

Women At Increased Risk For Breast Cancer Decades After Last Childbirth

In a new study published in the journal Annals of Internal Medicine on Monday, researchers looked at the data of nearly 890,000 women younger than 55 years old and found that women who have given birth may have increased breast cancer risk up to 23 years after their most recent childbirth.

The study found that the risk peaks at five years after childbirth but starts to fall after 24 years. The risk is at lowest 35 years after the birth of the woman's last child.

Minimal Risk

Study researcher Hazel Nichols, from the University of North Carolina at Chapel Hill's Gillings School of Global Public Health, and colleagues, however, said that women need not worry because the increase in risk is very minimal.

In women between the ages 41 and 45, there were just 41 more cases of breast cancer in every 100,000 who gave birth in the previous three to seven years than in women who did not have children.

By age 50, there were 247 more cases per 100,000 women in the group that recently gave birth.

"In this age group, breast cancer is uncommon," Nichols said. "The risk of developing breast cancer is still low overall, even if you've had a child five years ago."

Risks Vary

The findings may appear contrary to the conventional wisdom that childbirth provides protection against breast cancer. Researchers, however, said that childbirth is still protective albeit it can take more than two decades for the benefits to emerge.

According to the National Cancer Institute, pregnancy-related factors that are generally linked to lower risk of developing breast cancer later in life include having the first full-term pregnancy at an early age, breastfeeding over a longer period, and having more than one birth.

Factors linked to higher risk for breast cancer include having the first full-term pregnancy at an older age, having given birth within the last 10 years, a history of breast cancer in the family, and having taken diethylstilbestrol during pregnancy.

"Increases in breast cancer risk after childbirth were pronounced when combined with a family history of breast cancer and were greater for women who were older at first birth or who had more births," the researchers wrote in their study.