Four lesbian women are suing a U.S. state for discrimination for insisting women have unprotected sex with a man to prove they are infertile and claim insurance cover for treatment.

In a landmark case, the women filed the complaint after being rejected by their insurer for infertility treatment and arguing the law discriminated against infertile gay women by forcing them — not straight women — to pay for procedures.

Two of the women, Erin and Marianne Krupa, a couple, spent more than $25,000 on failed infertility treatment in five months after their insurance claim was rejected, the complaint said.