DENVER — Over the next few weeks, Coloradans will decide whether to ban gender-affirming surgeries for minors, though available data suggests few teens receive such procedures in this state.

Proposition 135 would outlaw surgeries to change a minor’s sexual characteristics for gender-affirming purposes. Currently, 26 states outlaw both gender-affirming medication and surgery for youth, though a handful have exemption processes. Arizona bars only surgeries.

No Colorado hospitals currently offer gender-affirming surgeries to minors. Medical provider groups have opposed the ballot initiative because of concerns about government interference in healthcare decisions. And the measure’s opponents held a significant fundraising advantage as of the end of September.

Patricia McKernan, director of the issue committee Protect Kids Colorado, said the initiative is necessary because children and teens don’t have the maturity to make decisions that could affect their future fertility. The group helped get the question on the ballot.

“It is truly just to protect children from decisions that will make it impossible for them to have children when they’re adults,” she said.

The limited data nationwide shows that almost all gender-affirming surgeries on teens involve the chest, which wouldn’t affect the ability to have children, though breastfeeding would likely prove impossible.

Most medical groups believe chest surgery should be an option for teens with severe gender dysphoria — distress caused by a mismatch between someone’s identity and how others see them. Treatment for gender dysphoria can also include non-medical changes, such as dressing differently, puberty blockers for preteens and hormonal therapy for teenagers.

Chris Cook, a Thornton resident who opposes Proposition 135, said his family moved from Kansas in 2023 to get away from an anti-trans political climate, as well as bullying of their transgender daughter in their neighborhood.

He said the family plans to defer any gender-affirming surgeries she might want until she turns 18, but for teens who have severe distress, waiting isn’t always safe. In addition, the ballot measure’s language is vague enough that he’s concerned it could outlaw the use of extended-release implants for puberty-blocking drugs, which his daughter will likely need in the near future.

“It’s rather alarming to put any precedent on where the government inserts themselves on what’s going on with the patient, the family and provider,” Cook said.

The ballot initiative comes at a time when the Trump administration is making an unprecedented push to halt gender-affirming care for minors, including threatening to cut off Medicare and Medicaid payments to any hospital that provides puberty blockers, hormones or surgeries to underage patients and sending subpoenas to hospitals for providers’ and patients’ records.

At least six hospitals across the country have agreed to stop providing gender-affirming care to end investigations by the U.S. Department of Justice, with two committing to offering “detransition” clinics.

The legal climate led Children’s Hospital Colorado and Denver Health to stop prescribing puberty blockers and hormonal treatments for gender affirmation late last year. A court order forced Children’s to officially reinstate those services, but none of its providers have agreed to offer them, citing fear for their livelihoods. A federal magistrate recommended throwing out a subpoena for Children’s patients’ records, but the Justice Department has appealed.

Proposition 135 would also prevent Medicaid and private insurance plans from covering gender-affirming surgeries, apparently removing the option for minors to seek surgery out of state.

The Colorado Department of Health Care Policy and Financing said the state’s Medicaid program hasn’t covered a gender-affirming surgery in at least two years. Data isn’t available on how many surgeries private insurance covered.

Pinning down how many young people receive gender-affirming procedures can be surprisingly tricky.

A study in the Journal of the American Medical Association showed an increase in gender-affirming chest surgeries among people under 18, from 100 in 2016 to 489 in 2019. A study using a different data source estimated only 85 gender-affirming procedures in 2019, however, after removing surgeries on teens without a gender dysphoria diagnosis. (Teen boys sometimes seek surgery after developing female-appearing breasts because of hormonal abnormalities or medication use.)

Medical groups oppose ballot measure

Five major medical groups came out in opposition to Proposition 135: the Colorado chapter of the American Academy of Pediatrics, Colorado Psychiatric Society, Colorado Medical Society, Colorado Association of Family Physicians and Colorado Child and Adolescent Psychiatric Society.

All said they opposed the ballot measure because it would interfere with decision-making by doctors, parents and patients.

The Colorado Medical Society doesn’t typically take positions on ballot initiatives, but opposes efforts to restrict clinical decision-making, president Dr. Sean Pauzauskie said. The same would be true if voters were deciding whether to restrict treatment options for any other condition, he said.

“Our members have diverse political views, but share the belief that medical decisions belong in the exam room,” he said.

In a statement, the Colorado Association of Family Physicians raised concerns that Proposition 135 could affect care for other conditions. The initiative’s supporters say it is written to only restrict procedures that would change a minor’s sexual characteristics for gender-affirming reasons.

McKernan said the ballot language would still allow circumcision, procedures to correct developmental abnormalities and surgeries on infants with atypical genitalia.

“What is prohibited in 135 is surgery that alters sex characteristics, attempting to change the gender of the child,” she said.

Contributions to the measure’s opponents dwarfed those to supporters.

As of Sept. 17, Families Not Politics reported about $741,511 cash on hand, and it received $548,917 by the end of the month. The largest contributors were the American Civil Liberties Union, Brighter Future for Colorado, the Colorado Organization for Latina Opportunity and Reproductive Rights, Advocates for Trans Equality and Cobalt Advocates.

Another opponent group, Vote Common Sense, reported $413,633 on hand and $151,500 in new contributions. The third-largest opponent committee, The People’s No, had $100,000 on hand and received $100,000 more.

On the other side, Protect Kids Colorado reported $78,756 cash on hand as of Sept. 17 and $17,036 in contributions through the end of the month. More than half of the new contributions came from the Family Policy Alliance Foundation in Colorado Springs.

Studies on outcomes of gender-affirming surgeries

Relatively few studies have specifically looked at outcomes in people under 18 who received gender-affirming surgeries. A poll with a small sample of American and Canadian transgender boys found that those who underwent chest surgery reported they were more comfortable in social settings and did more physical activity afterwards.

Small studies have also pointed to general improvements in body satisfaction and self-esteem among teens receiving gender-affirming care.

A 2025 study of adult transgender patients in the U.S. found those who underwent surgery had higher rates of depression and anxiety than those who didn’t. A different study, based on insurance claims, found the opposite result: lower rates of depression, anxiety and suicidal ideation among people who underwent gender-affirming surgery.

In both cases, the authors couldn’t definitively say that the surgeries improved or worsened mental health: a group seeking surgery might have had greater baseline distress, or the group that didn’t get it might include people screened out because of unstable psychiatric conditions.

The evidence that gender-affirming chest surgery succeeds in its most direct purpose — improving how patients feel about that particular body part — is stronger. Negative feelings about one’s chest appear to correlate with depression and anxiety in teenagers who identify as transgender males or nonbinary, though proving that improvement in one domain will extend to the others is challenging.

One study found most people who had body dissatisfaction or eating disorders in addition to gender dysphoria improved after starting gender-affirming care, but a subset had worsening symptoms. A different study, in Germany, didn’t find a significant group with worse body image, but did note that not everyone had the same improvement seen in the majority.

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