Warning: Public health officials have determined that not breast-feeding may be hazardous to your baby's health.

There is no black-box label like that affixed to cans of infant formula or tucked into the corner of magazine advertisements, at least not yet. But that is the unambiguous message of a controversial government public health campaign encouraging new mothers to breast-feed for six months to protect their babies from colds, flu, ear infections, diarrhea and even obesity. In April, the World Health Organization, setting new international bench marks for children's growth, for the first time referred to breast-feeding as the biological norm.

"Just like it's risky to smoke during pregnancy, it's risky not to breast-feed after," said Suzanne Haynes, senior scientific adviser to the Office on Women's Health in the Department of Health and Human Services. "The whole notion of talking about risk is new in this field, but it's the only field of public health, except perhaps physical activity, where there is never talk about the risk."

A two-year national breast-feeding awareness campaign that culminated this spring ran television announcements showing a pregnant woman clutching her belly as she was thrown off a mechanical bull during ladies' night at a bar — and compared the behavior to failing to breast-feed.