WASHINGTON — The federal government should consider cost in deciding which health benefits must be provided by insurance plans under President Barack Obama’s health care reform law, the National Academy of Sciences’ Institute of Medicine (IOM) says.

In addition, the cost of any new benefits should be offset by savings elsewhere in the health care system, IOM notes.

When defining essential health benefits, the government should try to guarantee that the average health insurance premium would not exceed benchmarks established by the secretary of the Department of Health and Human Services (HHS), according to IOM.

In a new report the institute does not detail services that should be covered but advises the HHS secretary on how to define minimum benefits — a decision that could affect about 68 million people, including individuals, families and businesses that obtain health coverage through new state-based insurance exchanges.

“Costs must be taken into account,” the panel says. “Unless we are able to balance the cost with the breadth of benefits, we may never achieve the health care coverage envisioned in the Affordable Care Act.”