Waterfront Media’s Everyday Health Network announced today that it will provide content to Yahoo! Health under a new partnership.

The deal will provide Yahoo! Health with content from several of the Everyday Health Network sites, including WhatToExpect.com, a parenting and pregnancy site, and SouthBeathDiet.com, among others.

“We’re very excited,” Mike Keriakos, president and co-founder of Waterfront Media, told MM&M. “Yahoo! Health is powering a substantial amount of content,” said Keriakos, noting that the company hopes the partnership will translate into unique viewers on the Everyday Health Network portfolio of sites—in numbers “significantly north of a million,” according to Keriakos.

Yahoo! Health will have access to any current and future content provided by the Everyday Health Network, with attributions and links back to the relevant Waterfront Media sources, the company stated in a release.

Keriakos cited comScore numbers in support of Everyday Health’s predominant position over WebMD, in terms of unique visitors—at least for the moment. “We’re highly confident that we’ll be ahead of WebMD during 4Q and 1Q,” said Keriakos, noting that he can’t predict what kinds of acquisitions or other initiatives WebMD might roll out in order to compete for viewers.

Yahoo! Health is the sixth largest online health site, according to September 2008 comScore data.