The Chubb Group of Insurance Cos. is now offering its medical benefits to transgendered employees and dependents.

Trevor Gandy, senior vice president and chief diversity officer for Chubb, called the move in a statement “a natural evolution for Chubb.”

Warren, N.J.-based Chubb cited Human Rights Campaign research that shows 39% of Fortune 500 companies offered transgender-inclusive health benefits this year, up from 1% in 2004.

Chubb is one of 70 major companies to file an amicus brief supporting The Gay & Lesbian Advocates & Defenders’ challenge of the Defense of Marriage Act, which imposes burdens on American businesses.