Four same-sex female couples have filed a lawsuit against the state of Tennessee, arguing that a law recently passed in the state will hinder their rights as parents.

The law in question was signed by Tennessee Governor Bill Haslam on May 5, which states that “undefined words” in state laws “shall be given their natural and ordinary meaning, without forced or subtle construction that would limit or extend the meaning of the language, except when a contrary intention is clearly manifest.”

The couples, all of whom are expecting children this year, argue that the newly signed law may prevent them from fully [exercising] their parental rights, as the state law includes language that uses the terms, “husband” and “wife.”

For instance, one Tennessee law states that a “child born to a married woman as a result of artificial insemination, with consent of the married woman’s husband, is deemed to be the legitimate child of the husband and wife.”

An appeals court in Tennessee had ruled recently in a separate case that a lesbian woman Erica Witt has parental rights to the child that was birthed by her previous wife under that law, as the court interpreted the term “husband” to include the female spouse of a “wife.”

“The legislature’s use of the words ‘husband’ and ‘wife’ merely reflects the fact that only opposite-sex marriages were recognized in Tennessee when the statute was enacted in 1977,” wrote Tennessee’s Attorney General Herbert Slatery in a memorandum. “After Obergefell, of course, that is no longer the case.”

Though the appeals court had previously ruled against Witt, the court reversed the ruling in May 2016.

Haslam’s bill requiring state laws’ terminology to be interpreted in their “natural and ordinary meaning” may complicate these issues, the plaintiffs argue.

Though backers of the law said that the law does not have to do with homosexuality or same-sex couples, Julia Tate-Keith, the attorney representing the four couples, argued that the law “absolutely is about denying gay people equal protection under the law,” Reuters reports.

David Fowler, president of the Family Action Council of Tennessee, said that these issues have arisen because “our law has abandoned the natural meaning of marriage,” as he told World Magazine.

“The problem is that giving a word a meaning contrary to its natural meaning requires us to give a new meaning to all the words associated with that word,” Fowler said.

The couples who filed the lawsuit include Elizabeth and Heather Broadaway, Kathrine and Emilie Guthrie, Charitey and Heather Mackenzie, and Crystal Dawn and Terra Mears.

A hearing date has not yet been scheduled, Tate-Keith told reporters.