For the first time in New Zealand two women can be named on a child's birth certificate as "mother" for children conceived using assisted reproductive techniques.
Jess and Stacy, who did not want to use their last names, complained to the Human Rights Commission after they were unable to both be listed as mums on the birth certificate of their daughter Evie.
It was then raised with the Department of Internal Affairs.
The lawyer who advocated for the "massive" change said it could affect more than 1000 children.
Solicitor and barrister Stewart Dalley, at Ryken and Associates, took on the case on a pro bono basis, after reading of their plight in the Herald last year.
Jess had told the Herald it had been frustrating filling out official documents.
She had to list her name under "other" on Evie's birth certificate and under "father" on their online application for an accommodation supplement.
"It's not good. Biologically she's my child and we're both equally Evie's mother.
"All they have to do is put a 'm' in front of 'other'. It's not difficult."
Today, Jess said the change meant a lot to the family.
"A lot of people have said it's just a piece of paper but it's a lot more than that..."
It recognised they were both equals as Evie's mums.
"It's not just about us either, there are a lot of couples out there that will hopefully benefit from this change.
"We have achieved something pretty big here... it's quite overwhelming actually."
Stacy said receiving Evie's new birth certificate in the mail had been surreal.
"I thought it was never going to happen because when I called up the DIA I was just told that they can't change it.
"I didn't actually think we would get to where we are now and so quickly."
The couple said they were both very grateful for what their lawyer and the department had done.
Dalley said initially the department held the position that there were legislative reasons why they could not both be listed as mother on the birth certificate.
"But this was news to me, when I looked at that I thought I couldn't see any legislative reason why that would be."
Many letters and views were exchanged over the course of several months, he said.
"Eventually the department said 'yeah, you're right' there is no reason for this'."
Two women can now be listed as "mother" and "mother", or "mother" and "parent", on a New Zealand birth certificate.
Women who would like to change existing certificates in light of this option can contact the department and make the change if they choose.
This would come at no cost to the people who wanted to make the change.
Dalley said it was about recognising legal parents equally and also recognising that not all people identify with a gender.
"This labelling of 'other parent' sounded a bit like you were subordinate somehow, that you were not a real parent.
"All credit to the Department of Internal Affairs for coming on board."
Dalley and his partner were the first same-sex de facto couple in New Zealand to jointly adopt.
"We won that case a couple of years ago, so I was aware of this issue."
Sometimes it was about waiting for the case to come along and knowing "here's the opportunity to change it".
A department spokesperson confirmed that the recording of parental titles on certificates, including births, marriages and deaths, had been expanded.
"The change will enable two female parents to both be recorded on a birth certificate as the child's 'Mother', where that child was conceived using assisted reproductive techniques [such as artificial insemination].
"Previously if the mother married or entered into a civil union or de facto relationship with a woman who consented to the mother undergoing the procedure, the details of the mother's partner could only be recorded as the child's 'parent' on birth certificates."