"The content was very emotional as opposed to research-based or informative," she said.
"The instructor spoke at great length about the drawbacks of medical intervention, the negative effects of having doctors involved in the birthing process, and the importance of not taking drugs for pain relief."
She added: "I was surprised to hear the teacher say that medically monitoring the foetal heartbeat during birth was harmful. I was also surprised to see taking castor oil recommended as a method of induction as I thought there were quite a few side effects and dangers to this old wives' tale. And to hear a number of statistics thrown about with no indication of the research behind them."
She described the class as "mostly one woman's opinions being pushed of a group of pregnant women".
Waitemata DHB's hospital services director Cath Cronin said the handouts given out at the class were not approved by the DHB and did not meet its standards. They had been produced by an individual staff member, and had not gone through the required approval process, she said.
"We are investigating how this occurred, as a matter of urgency," she told Fairfax.
Parents and expectant mothers who attended the course would be contacted, she said, and staff had been ordered to immediately remove any unsanctioned material.
The classes messages were condemned by a number of maternity and health groups, who said it contained "dangerous, frightening and scare-mongering advice about life-saving interventions".