The Master of the Rotunda Hospital says if more people using the hospital get vaccinated, more restrictions will be lifted.
The maternity hospital says the low vaccination rate among inpatients and their partners is partially the reason it is maintaining some COVID-19 restrictions.
It says just four in 10 of its patients are fully inoculated.
It says as soon as vaccination rates are higher among pregnant women and their partners they will lift restrictions once it is safe to do so.
But Professor Fergal Malone told Pat Kenny he is 'baffled' as to why partners of pregnant women do not have higher vaccination rates.
"I wasn't as surprised when I saw the 40% vaccination rate for pregnant women, because despite the fact... we have been strongly advocating the vaccine for pregnant women, there is a certain amount of vaccine hesitancy.
"But I cannot fathom why there is still about 60% of partners coming through the Rotunda [who] are not vaccinated.
"Now I'm hopeful that that is a temporary blip.
"But I would strongly encourage all pregnant women and their partners: get vaccinated.
"Because as soon as we have our patient vaccination numbers up in a high level - like the general population - we of course will lift any and all restrictions that we can safety do".
'Free for all access'
Prof Malone says the hospital is allowing as much access as it can.
"We already exceed the vast majority of the minimum requirements of the HSE is suggesting should happen for maternity care access during COVID.
"For example, it calls for a minimum of 30 minutes a day visiting time: at the Rotunda we've managed to have a five hour window - and indeed on the weekends nine hours window of visiting for patients".
Prof Malone says partners are also allowed in during early scans and the 20-week scan.
"The challenge is we can't have unrestricted access, free for all, like pre-COVID, simply because of how busy the hospital is, it's limited infrastructure and the high amount of ongoing COVID infection".
He says part of the issue is that, owing to the age of the building, there is no ventilation in parts of the hospital.
"The main waiting area for the ultrasound unit only has been 10 and 12 seats - so if there's 10 or 12 pregnant women sitting in those seats, and now there's 20 or 24 adults in general in a small waiting room with no ventilation, that's not safe".
In an earlier statement, the hospital highlighted "challenging physical infrastructure" in a building which is 275-years-old.
It noteed that maintaining a one-metre physical distance in many inpatient and outpatient areas "is not possible".
It said 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 said.
"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".