According to recent research, adult women who were breastfed as infants have a higher chance of not getting breast cancer than their counterparts who weren't. Oddly, this result didn't necessarily apply to first-born children. Women who reported they were breastfed as babies were 17 percent less at risk for getting breast cancer. This was not observed among women who were first-born however.

The mother's age at the time of birth was used to predict how many environmental contaminants were in her breastmilk, suggesting a possible link between the amount of contaminants and the woman's likelihood of developing breast cancer. Over 2,000 women between the ages of 20 and 69 with breast cancer and just under 2,000 at that age without it were studied. All three factors--the mother's age, the daughter's birth order and whether or not she was breast-fed--were given consideration for the study.

Women who were not breast-fed, reduced cancer risk was noted when the mother was older. Birth order did not affect this group, while in those who were breast-fed group it was noted women with three or more older siblings had a lesser chance of getting breast cancer than first-born women. As is the result with most research, more study is needed.