WASHINGTON - The number of individual applicants turned down for coverage by four large health insurers on grounds of preexisting conditions grew nearly 50 percent between 2007 and 2009, according to a congressional committee.

During that period, WellPoint Inc., Aetna Inc., Humana Inc., and UnitedHealth Group Inc. rejected 651,000 applicants for illnesses or conditions they had before applying for coverage, according to a report by the House Energy and Commerce Committee, led by Rep. Henry Waxman, a California Democrat.

Each company had a business plan to exclude preexisting conditions, it said.

The companies turned down 257,100 people last year who sought to buy benefits on their own and not through employers, the report said. They denied 172,400 such applicants in 2007, it said. Enrollment increased by 16 percent in that time, it said.

One company cited "improved preexisting exclusion process" as a way to increase business, said the report.

One of the companies had a list of 425 conditions that could be used to deny people insurance coverage, including pregnancy, diabetes and heart disease.

Other documents in the report showed that people who were surgical candidates, pregnant, female and "treated for infertility within the past five years," and "any applicant with a (body mass index) 39.0 or greater" were denied health insurance without any internal review.

The committee obtained the internal insurer documents in response to letters Waxman sent in March. The report didn't specify the insurers that carried out the actions it cited.

Insurers agreed to end denials for preexisting conditions early on during the health-care debate last year, said Robert Zirkelbach, a spokesman for America's Health Insurance Plans, the industry's trade group in Washington.

"In the current individual market, applicants undergo an underwriting process to discourage people from purchasing coverage only after they need medical services, which drives up costs for all policyholders," he said.

Donald Nathan, a UnitedHealth spokesman, declined to comment. Jill Becher a WellPoint spokeswoman, and Jim Turner, a spokesman for Humana, referred questions to the trade group. Fred Laberge of Aetna didn't return a message seeking comment.

The four insurers treat pregnancy as a preexisting condition and generally don't offer coverage to expectant mothers, the House committee said in a memo that cited company documents.