J.K. Rowling has angered Twitter users after making menstruation comments some people found to be "anti-trans".

The Harry Potter author shared an article that was titled: "Opinion: Creating a more equal post-COVID-19 world for people who menstruate."

Commenting on the phrasing of the article's title, Rowling wrote: "'People who menstruate'. I'm sure there used to be a word for those people. Someone help me out. Wumben? Wimpund? Woomud?"

This comment sparked an immediate backlash from Twitter users, who said that it's not just women who menstruate, pointing out the existence of intersex and trans people and the fact that after the menopause, women no longer have periods.

One Twitter user wrote: "J.K. Rowling is not even [subtly] transphobic anymore, and has apparently never heard of intersex people. [Every] day this woman makes me regret ever consuming a single word of hers."

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A second wrote: "I wonder if J.K. Rowling will stop being a woman when she reaches menopause."

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The children's author then posted again in response to her critics, writing: "If sex isn't real, there's no same-sex attraction. If sex isn't real, the lived reality of women globally is erased."

"I know and love trans people, but erasing the concept of sex removes the ability of many to meaningfully discuss their lives. It isn't hate to speak the truth."

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She continued: "The idea that women like me, who've been empathetic to trans people for decades, feeling kinship because they're vulnerable in the same way as women - ie, to male violence - 'hate”'trans people because they think sex is real and has lived consequences – is a [sic] nonsense."

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"I respect every trans person's right to live any way that feels authentic and comfortable to them. I'd march with you if you were discriminated against on the basis of being trans.

"At the same time, my life has been shaped by being female. I do not believe it's hateful to say so," the author concluded.

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However, this did nothing to quell Rowling's many critics on the social media site where she boasts 14.5 million followers.

Matilda actress Mara Wilson, who came out as bisexual in the wake of the 2016 Orlando shooting, reacted:

"Really sick of one of the richest and most influential white women in the world being lauded as some great crusader and truthteller for hating on one of the most marginalized groups of people."

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Whereas others slammed the author - a white, cisgender woman - for using her considerable platform to speak about trans issues in the midst of a race revolution and global pandemic.

One Twitter user wrote: "Truly pathetic that in the midst of huge outcry against police brutality and the unjust killings of black people by authorities, you choose to use your gargantuan platform and influence to attack a vulnerable minority?"

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Rowling was also labeled "transphobic" last year after she tweeted her support for a woman fired for stating "men cannot change into women".

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For those who are unaware of Maya Forstater, she was fired from her job as a thinktank researcher after an employment tribunal ruled that her opinions on biological sex were "absolutist", the BBC reports.

J.K. Rowling angers Twitter users with 'anti-trans' menstruation comments