(Reuters) – Mississippi’s Republican governor on Thursday signed legislation banning transgender athletes from competing in women and girls’ sports, the first U.S. state to pass such legislation this year.

Governor Tate Reeves had vowed earlier this month he would sign the bill, tweeting that the measure was needed “to protect young girls from being forced to compete with biological males for athletic opportunities.”

Some 37 bills regulating transgender athletes have been introduced in 20 states this year, according to LGBTQ advocates at the Human Rights Campaign.

“Governor Reeves’ eagerness to become the face of the latest anti-transgender push is appalling, as he chooses fear and division over facts and science,” said Human Rights Campaign President Alphonso David.

Idaho passed the first-of-its-kind “Fairness in Women’s Sports Act” last year, but it was blocked by a federal judge who found it unconstitutional.

(Reporting by Maria Caspani, Editing by Sonya Hepinstall)