Breastfeeding as Cancer Prevention

Brenda Phipps, B.S. Feb. 16, 2009

We’ve been hearing for years about the health benefits that babies gain through breastfeeding. In addition to reduced ear infections and fewer respiratory and digestive problems, breastfed infants - and their mothers - are likely reducing their risk for cancer as well.

            According to Food, Nutrition, Physical Activity and the Prevention of Cancer: a Global Perspective, published by the American Institute for Cancer Research, the evidence that breastfeeding protects women against both pre- and post-menopausal breast cancer is convincing. Protection against ovarian cancer is suggested as well, but that evidence is currently limited.

            Hormonal changes associated with lactation reduce a woman’s lifetime hormone exposure. According to experts, this seems to be the main reason women who breastfeed have a lower cancer risk. The American Institute for Cancer Research (AICR) also notes that physical changes that occur in breast cells while lactating may provide some protection as well.

            Although the rate of mothers initiating breastfeeding are increasing in the U.S., the number of mothers who breastfeed exclusively falls short of recommendations. According to the latest figures from the Centers for Disease Control (CDC), nearly 74 percent of women who gave birth in 2004 started breastfeeding. However, only 30 percent were breastfeeding exclusively at thee months and only 11 percent at six months. In 2005, the CDC reports 89 percent of Arizona women who gave birth started breastfeeding. That number fell to only 33 percent at six months and only 10 percent at 12 months.

            An exclusively breastfed infant receives only breast milk - no water, other liquids or solids. The AICR recommends women breastfeed infants exclusively for six months, introducing complementary foods such as baby cereal, fruit and vegetables gradually after that. This six-month target has been a longstanding recommendation aimed at maximizing the immunity benefits infants receive through the transfer of antibodies in breast milk. When other foods are introduced after six months, infants naturally reduce their consumption of breast milk. Decreased breastfeeding leads to less milk production and a return to pre-pregnancy hormone levels for the mother.

            The AICR reports babies are likely to receive cancer protection from breastfeeding, too. The evidence shows breastfeeding reduces the chances a child will be overweight for at least the early years of childhood. This is an important finding as being overweight in childhood tends to carry over into adulthood, and increased body fat clearly increases risk of at least six different types of cancer.

            Some mothers may choose not to breastfeed for a myriad of reasons. In these cases, there are other lifestyle choices that a new mother can make to protect both herself and her family from increased cancer risk. Do remember, however, that in terms of health benefits, while exclusive breastfeeding for the first six months is recommended, any time spent breastfeeding is better than none.

            What You Should Know About Breastfeeding provides information on common breastfeeding concerns. The brochure can be read, ordered or downloaded by visiting

            Brenda Phipps, B.S., is an international, board-certified lactation consultant at FMC’s Women and Infants’ Center. Is there a health topic you’d like to know more about? Please write to Mountain Medicine, c/o FMC Public Relations, 1200 N. Beaver St.  Flagstaff, AZ 86001, or visit FMC’s Web site at For more information, please see your physician.