Earlier this year, Coroner Garry Evans made strong recommendations for changes in the teaching and supervision of graduate midwives in his findings on the deaths of a mother and a newborn.
Australia already requires midwives to complete the equivalent of three years full-time post registration experience as a midwife and give evidence of current competence to provide pregnancy, labour, birth and postnatal care.
However, the Midwifery Council, New Zealand College of Midwives, and the Ministry of Health have all raised questions over the study's methods and data.
They all say that since the 2005 - 2009 period, when researchers looked at tens of thousands of births, various initiatives have improved birth outcomes for mothers and babies.
Midwifery Council chairwoman Associate Professor Dr Judith McAra Couper said the research failed to show causality between new midwives and increased perinatal mortality.
"So while one thing could be related to another, it does not tell us that one caused the other," she said.
The council also raised concern that the data was six to 10 years old and did not take into account the "many changes" that have taken place in midwifery education since 2009.
A review of the Midwifery First Year of Practice (MYFP), undertaken in 2012-2014 by the council, Ministry of Health, health officials, and the College of Midwives, was made mandatory in February.
"There was no evidence at all to show that this was the best and safest option for mothers and babies -- instead the evidence showed the best option was to strengthen the mandatory first year of practice programme," Dr McAra Couper said.
The New Zealand College of Midwives' chief executive Karen Guilliland said that since the study's data period, the rate of baby deaths during labour has significantly reduced, with 2015 currently sitting at an all-time low.
"Clearly the presence of highly educated midwives has improved the birth outcomes for babies. This is in contrast to the misguided claims made by Dr Lawton's study," said Ms Guilliland.
Ministry of Health's child and youth health chief advisor Dr Pat Tuohy welcomed the study but said further research, using more recent data, would be required to support its conclusions.
The University of Otago responded late this afternoon to stand by its "solid and robust" study, which was published today in the peer-reviewed International Journal of Gynecology and Obstetrics.
Dr Lawton was "disappointed" that both the College of Midwives and the Midwifery Council had "chosen to be defensive and attack" the research.
"The reality is, they need to look at these results, take them seriously and use them to improve quality," she said.
"This data, and recent tragic cases in New Zealand, make a convincing case for this to happen."
Consumer support network AIM: Action to Improve Maternity spokeswoman Jenn Hooper was not surprised by the study's findings.
She criticised the College of Midwives' defensive stance, saying it should instead be taking "a more constructive viewpoint that focuses less on themselves and more on good, safe outcomes for mothers and babies".
AIM next week plans to table a petition to the House of Representatives which raises concerns over current training requirements and a "lack of supervision" for newly-graduated midwives.
