Ms Thomson had been practising for about nine months when meeting the patient in July 2011 who was 16 years old and 10 weeks pregnant.
The tribunal decision found Ms Thomson did not provide adequate information to ensure the woman understood the labour process, including a birth plan and how to care for a newborn.
In the weeks following the birth the patient could barely walk due to a tear from the birth. When she did walk she feared the wound would open so she tied her thighs together with a dressing gown cord. Ms Thomson laughed when she saw what the patient had done which made the patient feel disparaged.
While at a doctor for a separate issue, the patient had the doctor check the tear which was found to be more serious than Ms Thomson assessed.
She was admitted to Wairau Hospital where it was confirmed the tear was infected and required reconstructive surgery.
The matter had been referred to the tribunal after a report by the Health and Disability Commissioner in July 2013 who found Ms Thomson's care was "seriously suboptimal" in this case.
Prior to these two reports the New Zealand Midwifery Council had also undertaken its own investigation, Ms Cole said. Ms Thomson was placed under supervision until December 2013.
"I believe that Natasha is now a much better midwife that will give women much better care," Ms Cole said. "She would never make that mistake again."
Action to Improve Maternity founder Jenn Hooper said she would agree with Ms Cole if the 18 months' supervision was actually supervision. Ms Hooper said she doubted it was.
"Unless you're there in that room how do you check what's in the notes really happened?" Ms Hooper said. "How do you know it hasn't just been lip service for 18 months?".
While Ms Thomson's practicing certificate was due to expire at the end of this month the council had no reason not to renew it, Ms Cole said. That would only be looked at if she had repeated the same mistakes or there had been a new complaint.
