Okla. Stat. tit. 25, § 1202

Vital statistics - Gender identification. The state, any political subdivision, or any state agency or department, including, but not limited to, public school districts, that collects vital statistics for the purpose of gathering accurate public health, crime, economic, or other data shall include, but not be limited to, the identification of any natural person who is part of the collected data as either male or female as defined in Section 16 of Title 25 of the Oklahoma Statutes.