A move by insurance companies to stop selling child-only policies is drawing criticism ahead of Thursday, when the federal health overhaul will require insurers to cover sick children.

Aetna Inc., Cigna Corp., WellPoint Inc., Humana Inc. and UnitedHealth Group Inc.'s Golden Rule subsidiary say they will no longer sell new child-only policies. The new law requires them to accept applications from sick children on insurance policies that they sell, but doesn't require them to sell a policy individually to children in the first...