The government moved Thursday to strengthen protections against discrimination for women, transgender people, the disabled and others who receive care throughout the health-care system, including those who buy insurance under the Affordable Care Act and providers that receive federal funding.

The ACA already bars discrimination based on sex and other factors, but the long-delayed proposed regulation issued Thursday explains how the protections will be applied to insurers and health-care providers, such as hospitals and doctors who receive Medicare and Medicaid payments, and it clarifies the standards federal officials would use in implementing the law. The proposed regulation comes as social attitudes about sexuality and gender are undergoing major shifts.

The proposal for the first time includes bans on gender identity discrimination as a form of sexual discrimination, language that advocacy groups have pushed for and immediately hailed as groundbreaking.

But the proposed rule does not provide specifics on other key protections that advocates have sought, such as including sexual orientation as a form of sexual discrimination. Officials said they are seeking more input during the comment period that ends Nov. 6 on how best to incorporate those protections. Nor does the proposal address something that many AIDS organizations say is discriminatory — when insurance plans make it difficult for HIV/AIDS patients to get access to and afford needed medications.

Under the proposed regulation, women could not be charged more than men for insurance or services because they need prenatal or maternity care. Insurers could no longer categorically exclude coverage for gender transition services, although they would not automatically be required to provide surgery or other care. Health-care providers could not refuse to treat transgender people. Individuals would need to be given access to bathrooms consistent with their gender identity.

The proposed rule, if finalized, would have a broad impact. It would apply to insurance companies that participate in the health law’s insurance marketplaces — a relatively small share of insured Americans — but also to all plans offered by these insurers. For example, because Aetna participates in the marketplaces, the rules would also generally apply to plans where Aetna offers insurance to an employer group or administers its self-insured plan.

Advocacy groups, many of which have been working with federal officials on aspects of the rule, praised the announcement. The National Women’s Law Center called it “a critical step toward full and effective implementation” of protection against discrimination. The National Center for Transgender Equality said it has “the potential to be life-saving for transgender people.”

“Advocacy groups have been waiting a long time for this, and it answers some important questions, but leaves others unanswered,” said Jennifer Kates, a vice president at the Kaiser Family Foundation.

Insurance industry experts said it’s unclear how much change is required to existing benefit requirements and what that could do to the cost of coverage.

Health and Human Services Secretary Sylvia Mathews Burwell said the proposed rule strengthens protections for some of the most vulnerable people in the health-care system, and gives every American access to the health care he or she deserves.

A doctor, for example, couldn’t ask a woman’s husband to be the guarantor of her payments if he didn’t ask the wife to be the guarantor for the husband. A dependent daughter couldn’t be denied maternity coverage if she is on her mother’s insurance.

Women have historically been underrepresented in medical research. The proposed rule expands existing nondiscrimination prohibitions in health research to ensure that no federally funded medical research discriminates against women.

“Women have to be treated equally to men in the health services they receive and the health coverage they obtain,” said Jocelyn Samuels, director of the HHS office of civil rights, in a phone call with reporters.

People who with limited English skills may also be eligible for interpreters and translators, so they could understand their diagnoses and treatments. The disabled may be able to demand access to interpreters or technology that helps them communicate with health-care providers.

Transgender people have long complained of widespread discrimination in the provision of health care, “from disrespect and harassment to violence and outright denial of service,” according to a 2011 report, “Injustice at Every Turn,” by the National Gay and Lesbian Task Force and the National Center for Transgender Equality, that is considered the most comprehensive survey of the difficulties they face.

In the survey, 19 percent reported being refused care, 28 percent were subjected to harassment and 2 percent said they were victims of violence in doctor’s offices. Half said they had to teach providers something about care for transgender or gender nonconforming people. That population reported more than four times the average rate of HIV infection.

A recent survey of physician resident trainees found that their knowledge and willingness to assist with hormone therapy increased from 5 percent to as much as 76 percent after a single educational lecture, according to endocrinologist Joshua Safer at Boston Medical Center. Safer, who is also an associate professor of medicine and molecular medicine at Boston University School of Medicine and his colleague Dylan Thomas, published their findings online last month.

Amy Ellis Nutt contributed to this report.