PROVIDENCE — A law requiring that health insurers provide infertility treatment benefits to married women will not be extended to include single women.

Governor Carcieri on Wednesday vetoed a bill introduced in March that would have mandated increased health-care coverage to include diagnosing and treating infertility in unmarried women.

In his statement, Carcieri said, “As a matter of public policy, the state should be encouraging the birth of children to two-parent families, not the reverse. By removing the marriage requirement, the legislation forces health-insurance companies to subsidize out-of-wedlock births.”

The message concludes: “Any further tinkering with this benefit is unnecessary and unwarranted, and allows for even further creeping of cost in our health-care system.”

Spokesman for Carcieri, Jeff Neal, said that the governor is concerned with overburdening the health-care system with additional mandates.

Earlier this year legislators passed a law requiring that coverage for infertility treatments include women up to age 42 and modified the infertility definition to mean unable to sustain a pregnancy during a period of one year. Insurers are already required to pay 80 percent of cost. They cannot deny coverage based on age, limit the number of treatments covered or total treatment cost. The provisions were meant for married women.

“It’s a question of where you draw the line on how much additional cost you put on health insurers,” Neal said yesterday. “The governor believes the two-parent family provides a more stable environment. It should be a public policy goal that children are raised in the most stable environment. We are speaking in very broad general terms. [It] is not meant to apply to any particular individual or circumstance.”

State Rep. Edith H. Ajello, D-Providence and other legislators don’t agree. They sought to create a bill that extended that additional coverage to all women, regardless of marital status.

The bill received General Assembly approval right before the session ended. It went to the governor last Friday.

“There are people living in commitment relationships, whether they are heterosexual or lesbian, who also provide a very good home life for children. I don’t think the state should be getting involved with who could be parents and who cannot. That’s very dangerous,” Ajello said. “In Rhode Island, single adults can adopt children, [unmarried] couples can adopt children, [and] lesbians can adopt children. I think this is appropriate.”

She added that language in Connecticut and Massachusetts state law does not include the word marriage in their infertility definitions.

Rhode Island is one of nine states that require insurance companies to cover infertility treatments. In Rhode Island insurers can charge subscribers a co-payment up to 20 percent.

Neal said with reports on the steadily rising cost of health care and companies passing those costs down to employees, and in some cases dropping coverage altogether, the governor is trying to find ways to alleviate that burden. Recently, a bill was passed to provide a new health-care option for small businesses.

“That’s a step in the right direction. While you are working on the one hand to lower cost, it’s a little contradictory to impose to new costs, which makes this a particularly difficult issue.” Neal said.

House spokesman Larry Berman said that, in this session, the governor has vetoed about 55 bills, the most in five years. Lawmakers will have to wait and see if House leaders will consider a veto override, he said.

“I think the word marriage is not appropriate in this day and age. We are recognizing that single women can be responsible and independent,” Ajello said. “Please show me what the increased costs would be. I think this is a civil-rights issue. Governor Carcieri ought to get with the times.”

lsparks@projo.com