According to a study, breastfeeding may offer broad protection against breast cancer that extends to women who delay having children.

Previous studies have shown that giving birth before age twenty five and having many children protects against certain types of breast cancer , while delayed child birth is associated with a higher risk of breast cancer.

The most important finding of the new study is that breastfeeding seems to lower the risk of developing breast cancer that comes from having children later in life according to an associate professor of preventive medicine at the University of Southern California and the study’s lead author.

Results of the study were announced at the annual meeting of the American Association for Cancer Research in Los Angeles.

“As more women may chose to delay pregnancy until after age twenty five, it is important to note that breastfeeding provides protection against both estrogen and progesterone receptor positive and negative tumors”, the associate professor said.

Women who develop breast cancer that is hormone receptor negative have a much poorer prognosis than women with other type of breast cancer.

The researchers analyzed data for women age fifty five and older, including 995 invasive breast cancer patients, and found that breastfeeding appears to have a protective effect regardless of when they started giving birth.

This is important since having many children was only protective among women who began having children at an early age. Evidence suggests that women who have children after age twenty five can reduce their risk of breast cancer by choosing to breastfeed, the associate professor concluded.

According to US Census data, twenty five is the average age that women in the US first give birth.

The study was funded by the National Institute of Child Health and Human Development and by the National Cancer Institute.