Mums giving birth will be asked to nominate a single loved one who will be permitted inside the delivery room and allowed access to the hospital during their stay.

While routine antenatal appointments will continue for now, antenatal classes and mother's groups will move to an online format.

The policy will also affect the families of terminally-ill patients, who will be asked to nominate one visitor, in a bid to keep numbers down at all public health services.

Canberra Health Service executive director Katrina Bracher said it was "with a heavy heart" that staff would be prevented from making exceptions for parents with a child in hospital.

The changes came into effect on Friday afternoon.

Ms Bracher said security staff had been employed to increase vigilance on what was a recommended one-visitor policy to what was now a requirement.

"Most people have been very, very supportive," Ms Bracher said.

"We took a soft-launch approach, so if people came to the campus and they didn't know the policy they weren't being pushed away.

"There have been a very, very small number people who have been upset at the new measures."

From Monday Canberra Hospital reduced its entry points from more than 40 to 12 in a bid to control visitor numbers. Those entry points were reduced to four on Friday.

The one-visitor policy is a further measure to combat the spread of COVID-19. Earlier in the week it was announced there would be a reduction in non-urgent and non-essential outpatient and community activity, and the suspension of all elective surgery other than category one and urgent category two announced earlier this week.

Outpatient services which have been reduced include vaccination services, dietician services, as well as a number of women's and children's health services.

Elective surgeries which would go ahead included some paediatric, some gynaecological and some maternity procedures.

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Ms Bracher said senior clinicians had been working with health service administration to determine which outpatient services and elective surgeries could wait, in order to minimise the risk to both patients and medical professionals.

She said hospital staff had begun making calls to reschedule appointments not prioritised as urgent.

Amber Harnisch gave birth to twins Addie and Arlen at Canberra Hospital eight weeks ago. She said no one could've predicted the changed world in which her and husband Andrew Harnisch were about to bring babies into.

Mrs Harnisch said the most difficult thing has been the daily changes of what was considered safe and what was not.

"The uncertainty is the worst thing," she said.

In keeping with social distancing, the Harnisch twins' extended family had been advised to stay away.

Police and Australian Defence Force personnel have been tasked with ensuring the Canberra public followed the "stay at home" message, Chief Minister Andrew Barr announced on Friday.

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