Dunedin feminist Charlie Montague says some voices are being silenced in the debate over trans women being able to self-identify as women.

Hostilities between some feminists and transgender activists are coming to a head as the sex self-identification debate heats up.

The two parties are arguing over who has the right to be designated a woman.

Trans Dignity Collective is lobbying on proposed changes to patient identification data – arguing the "concept of 'biological sex' is inherently derogatory towards trans people."

The collective "categorically opposes" the inclusion of a 'biological sex recorded at birth' field, which would "constitute a wilful refusal to treat trans people with dignity and respect."

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Dunedin feminist Charlie Montague says the debate over people being able to self-identify as women has become aggressive.

A public meeting hosted by campaign group Speak Up for Women, will be held on Thursday in Wellington to "peacefully" discuss conflicts between women's rights and proposed changes around self identification.

The collective's argument comes as a process is underway to make legal changes to sex on birth certificates easier.

Montague and some other radical feminists argue that allowing gender identity to trump biological sex will have far-reaching implications on women's hard-won rights, with men potentially impinging upon women's only spaces like changing rooms, prisons and women's refuges.

"Why are we replacing biology with ideology?" Montague said.

She says trans women are men, and "woman" was a biologically correct term that should remain the sole domain of adult human females.

"If I'm babysitting some girls and we go to the swimming pool and we're in the changing rooms and we notice a bloke is in there and I'm uncomfortable, then he says he's a woman would I have to ask him to leave? Or would we leave?"

Lesbians and feminists have been threatened, harassed and intimidated for their stance by trans activists with tactics designed to silence women in the debate, Montague claims.

The changes have been supported by Parents and Caregivers of Transgender and Gender Diverse Children spokeswoman Sharyn Forsyth.

"Given birth certificates are a generally accepted form of identity, being able to amend the gender marker to match their lived identity protects them from being 'outed' as transgender," Forsyth said.

MONIQUE FORD/STUFF Georgina Beyer has called for a less adversarial approach in the debate over gender identity self identification.

Georgina Beyer, the world's first openly transsexual mayor and MP, said both sides needed to display a willingness to consider the debate intelligently and urged trans activists to be less adversarial.

"They need to bring the public along with them .. if women are feeling their gender is under siege then they have a right to express their concerns – to label them transphobic is premature," Beyer said.

Earlier this month Wellington feminist Renee Gerlich's posters celebrating 125 years of women's suffrage were pulled by Phantom Billstickers over rainbow youth group's concerns they were transphobic.

"This whole idea of sex self-identification, that government now wants to enable as a one-step process, means we lose any robust, shared definition of sex. That in turn undermines all sex-based protections, which are especially important for women," Gerlich said.

BRAD FLAHIVE/STUFF Wellington feminist Renee Gerlich says sex self-identification means the loss of any robust, shared definition of sex undermining all sex-based protections, which were especially important for women.

"In short, these government proposals represent an unprecedented roll back of gains that women have fought hard for, and women need not only to be allowed to voice concerns about them – if this is a democracy, lawmakers should be actively seeking to hear women's concerns and objections, and should be setting up opportunities for those to be aired freely," Gerlich said.

Both Corrections and Department of Internal Affairs said they had provided advice on the Births, Deaths & Marriages Registration Bill currently before Parliament, and would see what happened.

* Clarification: This story has been amended to make it clear the views opposing sex self-identification are expressed only by some feminists, not by feminists in general.

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