Bakker and the student then went to the drug dispensary where the midwife told the student they would give the woman saline.
The labour progressed slowly and Bakker told the student to go back for more phoney pain relief on a number of occasions.
The tribunal said Bakker explained to the student her belief in the placebo effect.
"... [she] told the student midwife that the relationship between midwife and woman is like parent and child, with the midwife as the parent and the woman as the child.
Bakker "advised that the woman looks up to the midwife and listens to what she tells them, so that if the midwife tells the woman she is receiving pethidine, the woman believes her."
After a number of hours the woman finally did get the painkiller after a hospital obstetrician become involved.
The tribunal said the midwife's conduct amounted to malpractice.
She was fined $3500 and ordered to pay $10,000 in costs.
The baby was delivered safely.
The incident came to light because the student midwife told a different midwife what was happening while at the dispensary, who then reported it to the hospital.
After the patient was discharged from hospital, Bakker told the patient that she had not given her pethidine but had administered saline instead.
The tribunal said Bakker did not sufficiently communicate that the patient had received pethidine by way of intramuscular injection after the consultant's recommendation.
The patient initially believed that she had not been given any pethidine during her labour.
It was agreed that the patient told the Bakker she was glad about that. The midwife did not make any notes of that conversation.
The tribunal said Bakker had apologised to the woman and was sincerely remorseful.
She must undergo a standards review for the next two years, and cannot supervise student midwives for a year.