Hospitals aren't doing enough to encourage breast feeding among new mothers, according to a CDC report.

Across the country, just 14% of these institutions have a model written breast feeding policy in place, and the majority give infants food or drink other than breast milk when it's not medically necessary, according to the agency's August issue of Vital Signs.

Improvements may require "large cultural changes within hospitals," CDC director Thomas Frieden, MD, MPH, said during a press briefing, noting that many routinely give formula to all infants.

Frieden explained that some formula companies provide hospitals with the supplies they need for preemies and other special-needs infants who cannot breast feed at no charge as long as the hospitals put samples of formula in the goody bags they send home with new mothers.

Hospitals worry that changing this practice would cost them money, Frieden said, but, he countered, promoting breast feeding will in the long run reduce costs because it will lower the burden of illness in these children.

Another practice that fosters breast feeding is "rooming in," where infants stay with their mothers 24 hours a day rather than in a nursery -- a practice that has "been in existence for decades," Frieden said.

Yet just a third of hospitals keep baby at mom's bedside, according to the report.

The report is part of a wide-ranging government initiative to promote breast feeding, which research has consistently shown improves outcomes for both mother and child. Breast-fed infants have a lower risk of obesity, diabetes, sudden infant death syndrome, and a host of infectious diseases, and their mothers have a lower risk of breast and ovarian cancer, among other benefits.

In January, surgeon general Regina Benjamin joined other advocates to push for more women to start breast feeding and continue it for at least six months.

Currently, only 15% of mothers breast feed exclusively for six months, and just 44% are still feeding at all after that time, Frieden said.

And few hospitals -- just 4% -- have adopted at least nine of the 10 principles spelled out in the Baby-Friendly Hospital Initiative sponsored by the World Health Organization and UNICEF and 9% have adopted no more than two.

The 10 principles include helping mothers begin breast feeding within an hour of birth and encouraging community support of breast feeding, in addition to having a written policy, "rooming in," and banning supplementary feedings that are not medically necessary.

Just about half of hospitals help mothers initiate breast feeding within the first hour after birth, the report said. And only a quarter give mothers breast feeding support -- such as a follow-up visit, a phone call, or referrals to lactation consultants -- after they leave the hospital.

Frieden said that a previous CDC study found that the more WHO/UNICEF criteria a hospital met, the more likely it was that a woman would still be breast feeding two months later.

He noted, too, that low rates of breast feeding add $2.2 billion a year to medical costs, which is based solely on healthcare costs and doesn't include lost productivity or other costs.

Although more hospitals have adopted the "baby-friendly" criteria, progress has been slow, he said, and at current trends it would take 100 years before every U.S. hospital would be up-to-speed with the recommendations.

Data in the Vital Signs report come from the CDC's National Survey of Maternity Practices in Infant Nutrition and Care.

This article was developed in collaboration with ABC News.