New Hampshire would join more than a dozen other states requiring insurance coverage of fertility treatments under a bill that passed the House.

Supporters of the bill said the requirement would help the state attract young families as its population ages. They said they heard from many couples who said they work in Massachusetts in order to obtain coverage.

Opponents said they were concerned about the impact such a mandate would have on insurance premiums for small businesses.

The House passed the bill and sent it back to the Senate, which previously passed a different version.