The US national healthcare reform law has extended health insurance coverage to 17.6 million Americans, according to a new government report on Tuesday, up from its previous estimate of 16.4 million.

The number of uninsured has decreased because of changes in the law that allowed young people to stay on their parents' health plans for longer, the expansion of Medicaid in 29 states and the District of Columbia, and the sale of subsidized health insurance to individuals, U.S. Department of Health and Human Services (HHS) Secretary Sylvia Burwell said in a speech.

The previous estimate, which is calculated by a division of HHS, was issued in March.