The woman and her family said officer B spoke to her in an inappropriate way. She said she was shocked at being sworn at by the officer and began to cry.
"[Officer A's] failure to recognise the potential conflict of interest in allowing [officer B] to speak with you was undesirable," the report says.
"[Officer B's] approach to you and use of offensive language was undesirable."
The woman also complained about how she was treated while she was having a miscarriage.
She was not provided with clean underwear and was not adequately treated for her discomfort, she stated.
The IPCA report said the medical treatment she received while in police custody was "adequate" but police failing to arrange a change of underwear was "undesirable", as was the fact not all police officers were made aware of her condition.
The report said both officer A and officer B had breached the Police Code of Conduct and had been disciplined for their actions.
The IPCA has made recommendations to the Commissioner of Police in relation to policy regarding the provision of underwear for prisoners and the prominence of medical alerts.
Rotorua area commander Inspector Bruce Horne said it wasn't police policy to comment on employment or disciplinary matters.
"In respect of the recommendations made by the IPCA in their report, all have been acted on and implemented," he said.
"New Zealand Police has a very strong commitment to community engagement and the Rotorua police enjoy a very positive relationship with a broad range of partners in the community, including local iwi.
"Police managers are always willing to talk to people about any concerns they may have and working toward achieving a positive outcome for all parties."
