Under the existing rule, health insurers cannot place arbitrary limits or restrictions on health services that help a person transition from one gender to another. These services may include counseling, psychotherapy, hormone therapy and a variety of surgical treatments.

In the past, many insurers, as they denied coverage for such treatments, cited what they called the cosmetic or experimental nature of the procedures. The Obama administration said that view was “outdated and not based on current standards of care.”

But eight states, a network of Roman Catholic hospitals and the Christian Medical and Dental Associations, representing 19,000 doctors, challenged the Obama-era rule. A federal district judge in Texas temporarily stopped enforcement of the protections for transgender patients, saying that Congress had outlawed discrimination based on sex — “the biological differences between males and females” — but not transgender status.

“Congress did not understand ‘sex’ to include ‘gender identity, ’” said the judge, Reed O’Connor, in Fort Worth. In the Affordable Care Act, he said, Congress “adopted the binary definition of sex.”

But Jennifer C. Pizer, the law and policy director at Lambda Legal, a gay rights group, said, “That is an excruciatingly narrow and legally incorrect definition of the term ‘sex’ that would jeopardize legal protections for lesbian, gay, bisexual and transgender people.”

Doctors, hospitals and states in the Texas case also objected to a provision of the federal rule that they said put pressure on them to provide or pay for abortion-related services. The judge blocked this provision too.

Roger Severino, the director of the Office for Civil Rights at the Department of Health and Human Services, said it was necessary to re-examine the rule.