Dr Peter Boylan says he understands why the Rotunda Hospital is maintaining visitor restrictions and that they are 'clearly doing their best'.
The Rotunda says low vaccination uptake rates among pregnant women is partly the reason for maintaining the restrictions around partner visits.
A recent survey of inpatients there found 60% of patients and their partners are not fully vaccinated.
In a statement, the hospital highlights "challenging physical infrastructure" in a building which is 275-years-old.
It notes that maintaining a one-metre physical distance in many inpatient and outpatient areas "is not possible".
It says the Rotunda saw a 20% increase in births in the last year, with some 9,000 mothers due to give birth there in 2021.
"Recently, there has been a significant increase noted throughout Ireland in pregnant patients with severe COVID-19 illness", it says.
"We have tried to minimise the impact of COVID-19 restrictions on our patients' birth and pregnancy experience, however there are some maternity-specific and Rotunda-specific issues which have resulted in us needing to maintain some restrictions".
Dr Boylan, former Master of Holles Street National Maternity Hospital, told Newstalk Breakfast he can understand the hospital's position.
"I think it probably reflects partly, maybe, the population that the Rotunda serves.
"There clearly is a low vaccination uptake among people attending the Rotunda, and that does obviously create particular difficulties for them.
"They also note in their statement that they've had a 20% increase in births over the past year, and will have over 9,000 births this year.
"So you can kind of understand the difficulties that they have through basic over-crowding.
"The Rotunda's the oldest maternity hospital in the world, it's actually 275-years-old.
"And trying to run a modern maternity hospital in those circumstances with the increased numbers of births is really quite a challenge.
"So you can understand absolutely the distress caused to couples by not having their partner with them in particular circumstances."
He says the hospital is doing the best it can.
"I think they're clearly doing their best, but they do have a problem with the infrastructure in the Rotunda, and with the low vaccination rates among people attending."
While he says an apparent 4cm rule - that partners are not allowed in until the woman is dilated 4cm - is "really quite ridiculous.
"A woman is either in labour or she's not in labour - and if she is in labour, then her partner should be with her.
"And I do think the suggestion about antigen testing should be taken up and reviewed in a more logical way".
