Child welfare workers say they're appalled by the project and are taking legal advice over how to stop it.
Social worker Shannon Pakura said: "Child pornography is a crime and we want to do all we can to protect children from such exploitation."
Stuff website reports Auckland company Vixen Direct has defended its decision to film the birth, saying the baby's interests will be paramount.
Managing director Stephen Crow said: "I find this whole controversy quite amusing. Birth is the inevitable consequence of sex, and yet we're not allowed to show the two things in the same footage."
He told New Zealand National Radio there are no definite plans to show the child during childbirth.
The woman, identified only as Nikki, is due to give birth in November.
Ms Pakura, chief social worker with the Child Youth Family group, said: "Even using footage of the birth alone in such a movie is an affront to the child's dignity and future interests.
"We are taking legal advice over whether there is anything we can do to prevent the filming. At the very least we would want to try to prevent the distribution of a pornographic movie featuring the baby."
The country's Children's Commission, Roger McClay, believes the project is a breach of human rights. He said: "Who the hell do these people think they are. I'm going to protect this baby from being exploited."
