In a Facebook post, Richie said the decision to close would have a huge impact on Christchurch.
"Having been there with our two girls, the support and care was amazing and we can't let a facility like this shut," he said.
The Save St George's Birthing Unit petition was started by Christchurch organisation Rata Midwives about two weeks ago.
At 11am, they joined other campaigners on a march to the hospital to present the petition to chief executive Blair Roxborough.
Midwife Sheena Ross, who organised the petition, said she was thrilled with the response and hoped it would influence St George's decision-makers.
"The idea of delivering a petition in the Kate Sheppard Christchurch-style is something we really wanted to do.
"The thing we're most thrilled about is that it's been mainly grassroots, it's been the community. Ordinary families, ordinary whānau have come together going, no, actually we really love this service and we don't want it stopped."
Although it is private, St George's has a service contract with the Canterbury District Health Board to provide publicly funded maternity services.
Roxborough said they are working closely with their maternity staff who have been presented with the proposal.
"We do not want to pre-empt that process and we are seeking their feedback. We have huge respect for our maternity team and their right to be involved in this process.
"Our focus continues to be on providing information to our maternity staff."
The deadline for staff to provide feedback on the proposal is tomorrow.
Women can choose to give birth at a hospital, a primary birthing unit - for healthy people with no pregnancy complications - or at home.
Ross said midwives were deeply concerned St George's maternity centre would close, leaving Christchurch without a primary birthing unit until the DHB's new city unit opens next year.
She said home-like primary birthing units were ideal for women with uncomplicated pregnancies, but women would be forced to go to Christchurch Women's Hospital if St George's closed, stretching resources meant for acute care.
"If Christchurch Women's is too full, then those unwell women will have less access to care. There will be fewer beds available, they'll be sent home quicker postnatally. You can only stretch a service so far."
- Additional reporting RNZ