MONTGOMERY, Ala. (AP) — Alabama lawmakers are advancing legislation that would strictly define who is considered female and male based on their reproductive systems. Opponents said the move could erode the rights of transgender and intersex people in the state.

“There are only two sexes, and every individual is either male or female,” declares the Senate bill approved in committee on Tuesday.

It defines sex based on reproductive anatomy and says schools and local governments can establish single-sex spaces, such as bathrooms, based on those definitions. A House committee plans to take up similar legislation Wednesday.

The bills are part of a wave of legislation in Republican states that seek to regulate which bathrooms transgender people use, which school sports teams they can play on, and to prohibit gender-affirming medical care, such as puberty blockers and hormone therapy, particularly for minors.

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“I am here today to stand for women’s rights,” said Republican Sen. April Weaver, the sponsor of the bill. She said the definitions will guide courts in interpreting existing laws and “codifies the time-honored definitions of male, female, woman, man, boy, girl, mother, father, and sex.”

The bill states that a female is someone who, barring accident or anomaly, has a “reproductive system that at some point produces ova” and male as someone who, barring accident or anomaly, has a “reproductive system that at some point produces sperm.” The bill requires any state-supported entity collecting information related to sex to “identify each individual as either male or female at birth.”

During a public hearing, opponents said the legislation is part of ongoing attacks on the rights of transgender people to simply go about their daily lives.

“I’m here to say that I’m literally just a woman. I’m also transgender. People like me have always existed... and it’s OK that we exist,” Allison Montgomery told the County and Municipal Government Committee.

Montgomery said what proponents are seeking would mean that men who have “taken testosterone for years and have developed full beards” would be required to use women’s restrooms because their bodies once produced ova.

It is not clear how the proposal would impact people who are considered intersex, or born with a combination of male and female biological traits. The committee added language that sex can be designated as unknown on state records “when sex cannot be medically determined for developmental or other reasons.”

The legislation is at odds with decades of medical research showing gender is a spectrum, not a binary structure, and that sexual anatomy doesn’t always agree with the chromosomes and genes that cause most people to develop and identify as male or female.

The measure would create a vague exemption for people with intersex conditions — saying that individuals with congenital or medically verifiable differences in sex development “must be accommodated” in accordance with federal law — while declaring that such people “are not a third sex.”

Research indicates that the U.S. population of intersex people, born with physical traits that don’t match typical definitions of male and female, is even bigger than that of transgender people.

A proponent of the bill, Becky Gerritson, executive director of the Eagle Forum of Alabama, said the definitions would give guidance to the courts.

“This bill will help preserve those single-sex spaces which ensure privacy, safety, equal opportunity,” Gerritson said.

Democratic senators Linda Coleman-Madison from Birmingham and Merika Coleman from Pleasant Grove questioned the need for the bill.

“This is just so heartbreaking. We spend all of this time about trying to keep people down who are not like us. It’s sad,” Coleman-Madison said.