Faced with an uncertain future and struggling ad business, AOL is bulking up its AOL Health Web site, adding Caring.com, Health.com and HealthCare.com as three new partners.

HealthCare.com offers a list of more than 1 million medical doctors across the United States, depending on location, medical specialty, and health insurance plan; Caring.com features articles and guides on how to care for elderly patients; and Health.com offers articles, tips, images, videos and health tips for patients.

AOL says it seeks to create a "comprehensive network" of health-related information for families, but it still ranks far below competitors in terms of users. A slowdown in Internet advertising is also hurting the company, and parent Time Warner is reportedly trying to sell off the AOL unit entirely.

AOL launched AOL Body, which is now AOL Health, more than one year ago, but rebranded the site in an attempt to snap up more readers by expanding content to include different types of health care and fitness.

AOL Health is part of AOL's Living network, which also includes AOL Food, AOL Home, ParentDish, and StyleList. comScore statistics indicate the AOL Living network recorded as many as 16 million unique visitors last month.

Content sharing between different health sites is not uncommon, with RevolutionHealth.com, started by AOL co-founder and former CEO Steve Case, making several acquisitions and creating new partnerships to help it expand. AOL Health will share advertising revenue only with Health.com, and did not disclose why the others will not be included in the deal.

WebMD and the National Institutes of Health (NIH) remain the two most popular health sites on the Internet, with AOL Health not even in the top 10 health sites in the world. With so much ground to cover to make an impact, AOL Health will likely sign other partnerships to broaden its content in the future, but AOL officials did not disclose any future plans.