An influential pediatricians’ group affirmed its support for what activists call “gender-affirming” medical procedures performed on young people, though the group also called for a “systematic” review of existing evidence related to the controversial treatment regimens.

“Gender-affirming care” is the term for medical treatments that assist individuals in changing their bodies to look more like that of the opposite sex. Those procedures can include “puberty-blocking” drugs, synthetic cross-sex hormones, and surgeries such as mastectomies and castrations.

Advocates say such treatments are medically necessary for both adults and youth who claim to be members of the opposite sex, while critics say the evidence of the safety and effectiveness of those treatments is sparse or nonexistent.

In a statement last week, the American Academy of Pediatrics (AAP) said its board of directors had voted to reaffirm its 2018 policy statement in support of those treatments and that it had further “authorized development of an expanded set of guidance for pediatricians” pending a “systematic review” of available treatment guidelines.

The updated policy “will reflect data and research on gender-affirming care since the original policy was released,” the AAP said.

The academy said it had voted to reaffirm the older policy and update it due to “the board’s concerns about restrictions to access to health care with bans on gender-affirming care in more than 20 states.”

Numerous Republican-led legislatures across the country have in recent years passed laws that outlaw many transgender medical procedures for children, including irreversible surgeries that can leave young men and women sterilized for life. The AAP said in its statement that it “opposes any laws or regulations” that “discriminate” against transgender-identifying individuals.

Much of the criticism against transgender ideology has historically come from conservative-leaning activists and institutions, though in recent years a small but growing number of nonpartisan critics has arisen to voice concerns over the push to allow children access to transgender medical procedures.

A group of nearly two dozen international doctors last month signed an open letter warning medical officials of “exaggerating the benefits and minimizing the risks” of those treatments for children.

Those risks, they argued, “are significant and include sterility, lifelong dependence on medication, and the anguish of regret.”

Multiple European countries, meanwhile, have recently passed restrictions on transgender treatments for youth. England’s National Health Service, for instance, last year warned that gender “transition” procedures can have “significant effects” on a child’s “psychological function.” Sweden also recently rolled back government approval for youth transgender treatment.

The U.S. bishops in June voted to issue a significant revision to medical guidelines concerning transgender patients, strengthening prohibitions against transgender-related surgeries being performed in Catholic medical facilities.

The bishops in an earlier document had said that Catholic institutions were not permitted to “perform interventions, whether surgical or chemical, that aim to transform the sexual characteristics of a human body into those of the opposite sex.”