But those who consume more omega-6 fatty acids may be shortening the odds of their daughters developing the disease.
Both omega-3 and omega-6 are essential to a healthy diet, but omega-6 occurs more commonly in typical Western diets in foods like meat, eggs, poultry, cereals, breads, baked goods, vegetable oils, and margarine.
"Inadvertently, we may be setting up our daughters to develop breast cancer 50 years from now," said Dr Elaine Hardman, an assistant professor in the division of functional foods at the Pennington Biomedical Research Center, Louisiana State University, who carried out the study.
Omega-3 fatty acids are found in fish, especially tuna, salmon and mackerel, and in canola and flaxseed oils, soybeans and nuts. Their protective effects may also continue when offspring are fed a diet rich in omega-3 after weaning and at least until puberty.
Hardman carried out her research using mice, which allowed her to observe the effects of diet throughout a lifetime but condensed into a matter of months.
The mice were bred to have a genetic predisposition to breast cancer. The mothers were fed diets high in either omega-6 fatty acids or omega-3 fatty acids during the gestation period and while breast-feeding their female young.
After weaning, one group of female offspring was placed on a high-omega-6 diet and the other was fed mostly omega-3.
Hardman found that all the young exposed only to omega-6 fatty acids at all three stages (in utero, in nursing and after weaning) showed mammary gland tumors by six months of age.
However less than 60 percent of those that ate a high omega-3 diet either in utero or post-weaning had formed mammary tumors by the age of eight months.
Just 13 percent of the mice fed omega-3 in utero and after weaning developed tumors by the age of eight months.
The reason behind these results may be that omega-6 increases maternal levels of estrogen, which has been linked to increased incidence of breast cancer in female offspring, while omega-3 is thought to decrease it.
The American Cancer Society estimates that 211,240 new cases of breast cancer will occur in the US this year, and 40,410 women will die from the disease.