Scout Barbour-Evans, who contested the Dunedin mayoralty in 2016 and came close to gaining a council seat, said having a birth certificate with female on it was ''wrong''.
Barbour-Evans also opposed the stance of the Lesbian Rights Alliance Aotearoa (LRAA), which is against the change.
If Parliament adopts the recommendations of the Governance and Administration Committee on the Births, Deaths, Marriages and Relationships Registration Bill, people wanting to change their birth certificate gender could do so without needing confirmation by a judge.
The move would bring it in line with passports and drivers' licences.
It would also offer options others than male or female, with ''intersex'' or ''X (unspecified)'' also available.
The LRAA said it would make it impossible for females to retain the right to female-only or lesbian-only spaces, services and provisions, because any male could simply declare he was female and have every legal right to use them.
''This move risks the safety of women in prisons, the continuation of women-only and lesbian-only organisations, and ultimately renders the sex discrimination protections in the Human Rights Act meaningless.''
Barbour-Evans responded there was a high proportion of transgender people who experienced high levels of depression and self harm.
Excluding those people from groups that were supposed to be supportive of women and girls was potentially going to harm people further.
Barbour-Evans was ''very keen'' on allowing genders to be changed on birth certificates by way of a statutory declaration.
''I'm pregnant at the moment. My child will be calling me Dad, and it means a lot to me, and to my family and my community, that I don't have to lie on formal and legal documentation about the birth of my child.''
Barbour-Evans said having a birth certificate with ''female'' on it was ''wrong''.
''Every single time I use my birth certificate it feels like I'm lying. It feels like I'm breaking the law, because I can't be honest the way that the laws are set up.''
While Barbour-Evans' birth certificate has not been changed through a court process, Barbour-Evans' passport has an ''x'' in the gender box.
That involved filling in a new passport form, then seeing a justice of the peace.
''I found it really easy.''
But Barbour-Evans said there had been situations where the gender on documents - Ministry of Social Development documents were an example - was wrong.
MSD required a birth certificate to change gender.
''It's just hard. All I want to do is be honest.
''The reality is the only person it's hurting is me. The only person these rules hurt are the people who have the incorrect thing on our birth certificate.''
- Additional reporting by NZME
