The World Health Organization (WHO) will remove "gender identity disorder" from its global manual of diagnoses — a major win for transgender rights. The change was announced last summer, but a resolution to amend the health guidelines was officially approved Saturday.

The United Nations' health agency released a revised version of the International Classification of Diseases (ICD) that reclassifies "gender identity disorder" as "gender incongruence," which is now featured under the sexual health chapter rather than the mental disorders chapter.

Gender incongruence is better known as gender dysphoria, the feeling of distress when an individual's gender identity is at odds with the gender assigned at birth. An evolving scientific understanding of gender and work by transgender advocates have contributed to the reclassification.

Good news! Major update to World Health Organization guidelines.@WHO removes “Gender Identity Disorder” diagnosis – time for governments worldwide to update laws and procedures to respect transgender people’s rights: https://t.co/QvAD9IHdtm pic.twitter.com/NF8YHb9pBa — Human Rights Watch (@hrw) May 28, 2019

"The WHO's removal of 'gender identity disorder' from its diagnostic manual will have a liberating effect on transgender people worldwide," Graeme Reid, LGBT rights director at Human Rights Watch, said in a statement Monday. "Governments should swiftly reform national medical systems and laws that require this now officially outdated diagnosis."

In many countries, transgender people must be diagnosed with a "gender identity disorder" in order to be approved for various aspects of their transition — from changing their name on their driver's license to undergoing gender confirmation surgery. The reclassification may allow transgender people to seek medical care without being considered "mentally disordered."

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The new classification "represents a major step in global transgender health and rights," Kyle Knight, researcher in the LGBT rights program at Human Rights Watch, told CBS News Tuesday. In Japan, "the government has been an ardent supporter of LGBT rights internationally and at the United Nations, but still upholds a 2004 law that mandates a diagnosis of 'GID' plus several surgeries — including one that sterilizes the patient — in order for trans people to change their legal gender."

"It's far past time for governments like Japan, or the dozens in Europe that have similar laws, to change them," Knight said. "Trans people shouldn't be subjected to mandatory diagnoses or medical procedures just to get their basic rights."

Globally, both the ICD and the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) are used to diagnose patients. The American Psychiatric Association last revised the DSM in 2012 to remove the term "gender identity disorder" from the manual and add the term "gender dysphoria." Now, the ICD is making a similar change.

"Reclassifying trans and gender diverse people in ICD-11 will make a big difference," Mauro Cabral Grinspan, activist and executive director of GATE, told CBS News Wednesday. "It basically means that trans and gender diverse people stop being considered mentally disordered just because of who we are — an assertion that was proven to be not only arbitrary and unfair, but also incompatible with WHO scientific standards."

The change comes as the Trump administration has been taking action to repeal protections for transgender people in the United States. The Health and Human Services Department announced Friday a rollback of health care regulations protecting LGBTQ people. The day before, the Department of Housing and Urban Development announced a new rule proposal that would undo Obama-era protections for transgender people at homeless shelters. In April, President Trump's transgender military ban went into effect.

In a win for transgender rights, the U.S. Supreme Court decided Tuesday not to take up a challenge to a Pennsylvania school district's policy allowing transgender students to use bathrooms and locker rooms that correspond with their sexual identity. The justices rejected an appeal from students who argued that allowing transgender students to use the same facilities violated their right to privacy.

WHO's 194 member states have three years to put the new changes into practice at the national level, with a target deadline of Jan. 1, 2022.

WHO also adopted changes that include recognizing "burnout" at work as an "occupational phenomenon" and "gaming disorder" as a form of addiction.