UnitedHealth Group Inc., Aetna Inc. and Humana Inc. plan to retain some benefits created by the U.S. health-care overhaul even if the Supreme Court strikes down the law. The exception: Those involving people with pre-existing illness.

Customers of UnitedHealth, the largest U.S. health insurer, can keep children on plans until age 26, get free preventive care and won't face lifetime benefit limits, the Minnetonka, Minnesota-based company said yesterday in a statement. The insurer also won't rescind policies except for cases of fraud and will retain a simplified appeals process for denials.

Aetna, the third-largest health insurer by market value, said today it would cover preventive services, let young adults stay on their parents' plans and continue outside reviews of coverage denial appeals. Industrywide implementation of those and other provisions of the 2010 health care law has been in doubt as the Supreme Court prepares to rule this month on whether a key measure of the overhaul is constitutional.