She reviewed the woman, called the specialist and made a plan to try forceps delivery and, if that failed, to proceed to a caesarean section.
Recollections of the conversation between the two doctors differ. The registrar understood she was to carry out the procedures unsupervised; the specialist understood he was to attend.
The registrar began the forceps delivery. It failed. She proceeded with the caesarean.
The specialist had arrived at the delivery suite at the time these procedures commenced, but was called to assist with another obstetric emergency first.
"The obstetrics registrar was unable to deliver the baby as the baby's head was impacted in the pelvis," the commissioner's office said. "The obstetrics consultant arrived shortly after, and delivered the baby.
"The baby was born white and floppy with the umbilical cord wrapped around her neck. The baby was resuscitated and transferred to the neonatal intensive care unit, but sadly passed away."
Mr Hill said the DHB breached the code as it failed to ensure its staff were sufficiently supported and its policies followed - in particular its policies for assessing and prioritising obstetric emergencies, its "senior medical officer cascade process", and the need to inform the registrar of the necessary level of supervision.
The specialist's breach was in not properly supervising the registrar.
"Consultant oversight and input provides an important safety net," Mr Hill said. "As the senior supervising clinician, the obstetrics consultant had a responsibility to ensure that his instructions were communicated clearly, and that they were understood."
Mr Hill expressed concern over how long the specialist took to arrive at the hospital and that he did not obtain an update on the woman's condition before attending the other obstetric emergency.
He criticised the registrar for proceeding with the delivery unsupervised and not recognising that she was "out of her depth".
"However," the commissioner' office said, "the registrar had not been informed of the DHB's credentials and supervision requirements, believed that the consultant had instructed her to proceed unsupervised, and the clinical situation was worsening and there was no senior consultant available immediately."
Consequently Mr Hill did not find that she had breached the code.
Both of the doctors and the DHB have apologised to the woman and her husband. Mr Hill recommended the DHB take a number of actions to improve the quality of its services.