"Quite why it didn't see the light of day I'm not sure," she said.
The report said unhelpful academic year scheduling - with universities' holidays out of sync with school holidays which penalised primary caregivers - and a tendency for male staff to informally mentor young men were major barriers to increasing women's participation.
Ms McNabb said women now accounted for 76 per cent of tertiary graduates, but the pace of change in universities at the upper tiers was glacial.
"What is happening is too slow - tiny little improvements - when we ought to be leading the way in terms of women in senior positions."
An AUT spokeswoman said the report was not made public as it was "commissioned for internal use only".
The spokeswoman said AUT had taken steps following the report to improve gender equity, including leadership programmes for female staff, and had improved on the proportion of senior academic staff to 26.8 per cent in 2012.
Meanwhile Equal Opportunities Commissioner and former National MP Jackie Blue has written to Deputy Prime Minister Bill English to offer practical solutions in a landmark equal pay case.
The Court of Appeal has ruled in favour of Lower Hutt aged-care worker Kristine Bartlett, who claimed it was unfair and in breach of the Equal Pay Act of 1972 for her to be paid only $14.46 an hour after 20 years working at the same rest home, when men in other occupations with similar skills and responsibilities were paid more.
Business New Zealand says the effect will be limited, especially if the Supreme Court overturns the decision or the Government changes the law to stop any knock-on claims.
"My view is that the potential impact of the case is far-reaching," Dr Blue told the Weekend Herald .
"The outcome could extend to female dominated occupations that are better paid but which are nevertheless undervalued."