California Code, Insurance Code - INS § 10140.2

(a) Notwithstanding Section 10140, a health insurance policy issued, amended, or renewed on or after January 1, 2011, shall not be subject to premium, price, or charge differentials because of the sex of any contracting party, potential contracting party, or person reasonably expected to benefit from the policy as a policyholder, insured, or otherwise.

(b) For purposes of this section, “sex” shall have the same meaning as “gender.” “Gender” means sex, and includes a person's gender identity and gender expression.  “Gender expression” means a person's gender-related appearance and behavior whether or not stereotypically associated with the person's assigned sex at birth.