Experts and professionals remain unconvinced that babies are more at risk if delivered by a private midwife instead of a doctor.

A report from the University of Otago showed an increase in conditions like asphyxia and other neonatal complications when a midwife was in charge.

The Wellington-based researchers studied more than 244,000 pregnancy outcomes between 2008 and 2012.

However Lesley McCowan, professor of obstetrics and gynaecology at Auckland University, said those babies born under a midwife, and those under a doctor, were very different groups of people.

She said the differences reported in the births of these babies could not be put down to mishandlings by a midwife.

Professor McCowan said midwives are actually responsible for a reduction in stillbirths in New Zealand, and the study does not prove otherwise.

Dr Ian Page, who is the Chair of the New Zealand Committee of the Royal Australian and New Zealand College of Obstetricians and Gynaecologists, believes women and families shouldn't be frightened into thinking there're serious problems with the maternity system.

"[The report] needs far more detailed assessment and analysis and we would agree with that, but we would not agree with people drawing the conclusion that there's a major problem with the system," Page said.

"They should be saying, as the Ministry, ourselves, and the College of Midwives have said: 'It's an interesting observation and it's worthy of further analysis."