The widespread use of electric breast pumps by American women is fueling a "quiet revolution" in how infants receive their mothers' milk, argues Cornell nutritionist Kathleen Rasmussen in a commentary published online June 16 in the American Journal of Public Health.

Once limited to hospitals and clinics, in the past two decades pumps have become high-powered and portable, as commonplace to modern motherhood as diaper bags and pacifiers. Women are known to extract and save significant quantities of breast milk at work, after feedings, in public restrooms or even while driving.

Rasmussen and co-author Sheela Geraghty, M.D., pediatrician and medical director for the Cincinnati Children's Center for Breastfeeding Medicine, call for study of such changing breastfeeding habits "to document the consequences -- good and bad -- of milk expression as currently practiced for the health of infants and their mothers."

"More and more women are using breast pumps to express and store milk -- one study found that 85 percent of mothers had done so -- but there are still many unknowns in the scientific community about the advantages and disadvantages to mothers and to babies from this practice," said Rasmussen, professor of nutritional sciences. "The current data, for example, counts all breast milk as the same -- whether the infant consumes it at the breast, if it's bottle-fed or if it comes from another woman. We need a better understanding of how and why women are pumping."

On the one hand, the authors write, it could be that pumps allow more women to feed their babies human milk, and for longer periods. (The American Academy of Pediatrics recommends that infants are fed exclusively breast milk for the first six months of life and for mothers to nurse throughout the first year.)

But bottle-feeding of human milk also presents problems for mothers and their children. Ill-fitting pumps can irritate women's breasts, and over-expression of milk can increase supply to the point of discomfort. As milk is collected, stored and thawed, sometimes in unsanitary conditions, there are risks of contamination and diminished nutritional and anti-infective benefits.

"There are many benefits for both mothers and infants when the infant directly feeds at the breast of the mother, but we do not know if these same benefits are realized when women pump and store their milk," Geraghty said.

To be sure, high-tech breast pumps have been a boon to women unable to nurse and to working mothers, giving them an option to produce and feed milk to their babies. But there is growing evidence that even women without such challenges are choosing to express their milk and bottle-feed it to their babies.

"We need a collective understanding as to why mothers in the United States have resorted to breast milk pumping instead of directly feeding at the breast," Geraghty said.

Ultimately, Rasmussen argued, clear findings of how breast pumps are used by American women would lead to better clinical advice for nursing mothers.

"We're seeking a balanced picture of what this rapid change has meant for mothers and infants," she said. "If we can answer the questions we're asking, we'll be able to educate women on how to best use pumps for the nourishment and safety of their babies and for their own health."

Ted Boscia is assistant director of communications for the College of Human Ecology.