The data published on Thursday by the Australian Institute of Health and Welfare comes amid ongoing concerns about overcrowding at Canberra Hospital's maternity ward.

The figures showed the average length of stay for a vaginal birth in an ACT public hospital was 1.4 days, the lowest in the country.

The average length of stay for a public caesarean section birth in ACT was the equal lowest at 2.7 days.

The ACT also had the highest rate of mothers leaving hospital the same day as birth at 9 per cent, according to the 2017-18 data.

ACT Australian Medical Association secretary Steve Robson - who is also an obstetrician - said doctors had concerns about a national trend to shorter lengths of stays, because many complications were not immediately apparent after birth.

He said capacity issues at Canberra Hospital's maternity ward no doubt affected how long women stayed in hospital after birth.

Following previous criticism from anonymous staff, Canberra Hospital maintained patients were never discharged until it was clinically appropriate.

Health Minister Meegan Fitzharris said the government was working to upgrade Canberra Hospital's maternity wards and recently refurbished Calvary Public Hospital's maternity ward.

The average length of stay for vaginal births across Australia is trending downward, sitting at 1.7 days.

Queensland had the next shortest average length of stay for public vaginal births at 1.5 days.

Women in the Northern Territory had the longest average length of stay at two days.

Dr Robson said for women to be discharged within a day they needed to have rock solid processes in place to make sure they were monitored.

He said there were well-documented capacity issues at Canberra Hospital that needed to be addressed.

"It is very difficult to get beds there and of course that means the more women who are discharged the more you can get a bed for someone who has just had a baby," he said.

"One of the things the government has gone to a lot of trouble to do is attract people from the private hospital system which means there is actually some capacity in the private system.

"The state and territory governments seem to be trying to attract people to public maternity and a lot of questions have come up about attracting people with private insurance so it goes into the income of the public system.

"That's all well and good but you have to have the capacity to provide the care."

The data also showed the growth in the number of patient separations at Canberra's public hospitals slowed last year to .5 per cent, below the average growth of 2.1. Since 2013-14 however, separations have risen 4.6 per cent.

Ms Fitzharris said the data showed the ACT was managing increases in demand for public hospital services, noting the territory had the highest growth in emergency admissions involving surgery across the country.

"This impacts on services, which is why there is comprehensive work happening right across our system to plan and better manage and sustain our services for an ageing population," she said.

"In recent budgets, we have delivered major boosts in funding for front-line services and staff and to improve access to surgical care and to reduce wait times."