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Texas’ transgender student athletes will be restricted from playing on K-12 school sports teams that align with their gender identity under a bill Gov. Greg Abbott signed into law Monday.

House Bill 25, authored by state Rep. Valoree Swanson, R-Spring, will require student athletes who compete in interscholastic competition to play on sports teams that correspond with the sex listed on their birth certificate at or near their time of birth. It is set to go into effect Jan. 18.

The legislation goes further than current rules from the University Interscholastic League, which governs school sports in Texas. Under current UIL rules, a student’s gender is determined by their birth certificate. But UIL also accepts legally modified birth certificates in which someone may have had their sex changed to align with their gender identity.

HB 25 adds to the arsenal of conservative victories Republican lawmakers have garnered throughout legislative sessions this year.

Swanson has argued that the bill intends to ensure fair competition in girls’ sports and uphold Title IX, a federal law that prohibits discrimination in education on the basis of sex.

“It’s so very, very important that we protect everything that women have gained in the last 50 years,” Swanson said during a committee hearing.

But advocates for transgender Texans have claimed the argument is not only detrimental to transgender youth but also cisgender girls and women who may not adhere strictly to societal standards.

Rebekah Bryant, whose 8-year-old daughter Sunny is transgender and testified against HB 25, last week said she felt “defeated” when the bill initially passed in the House.

“I’m feeling very defeated and very deflated right now, and I was sad to tell Sunny because we’ve always filtered her from the badness of all this as much as possible,” Bryant said.