A bill that bans Texas transgender girls from participating in female school sports was officially signed into law Monday by Gov. Greg Abbott. The bill goes into effect on Jan. 18.

House Bill 25 was sponsored by State Rep. Valoree Swanson, a Republican. “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.

The bill overrules the University Interscholastic League, which had only asked for students’ birth certificates, including modified birth certificates. The bill affects students from elementary school to college.

"We need a statewide level playing field," Swanson said on the House floor earlier this month. “It’s very important that we, who got elected to be here, protect our girls.”

Equality Texas, an LGBTQ advocacy group said in a statement on Monday that “if Texans want to protect children, the goal shouldn't be to prevent trans kids from participating in sports, but to give all kids the freedom to make friends and play without fearing the kind of discrimination many older trans people face on a daily basis.”

Several other states have passed similar legislature including Alabama, Arkansas, Florida, Mississippi, Montana, Tennessee and West Virginia.