MI HB4190

Prohibits physicians from performing gender reassignment surgery on minors, including both genital procedures (such as hysterectomy, orchiectomy, vaginoplasty) and nongenital procedures (such as breast augmentation, facial feminization, voice surgery)

Bans physicians from prescribing cross-sex hormones (testosterone, estrogen, progesterone) or puberty-blocking drugs to minors when intended to assist with gender transition

Allows continuation of hormone or puberty-blocking treatment only for minors who have been Michigan residents since the law's effective date, were already receiving treatment before that date, and whose physician has documented that stopping treatment would cause harm

Defines "biological sex" based on chromosomes, hormones, gonads, and genitalia present at birth, excluding psychological or subjective experience of gender

Requires physician compliance with these restrictions as part of the Public Health Code