The charity Depaul has said it has seen an increase in the number of pregnant women accessing its homeless hostels.
Figures released to RTÉ's Morning Ireland show that there were 27 pregnant women sleeping in Depaul's homeless accommodation last year.
Nine pregnant women have accessed the charity's services so far this year.
Depaul said the women are generally staying in their "one night only" hostels and add that the figures captured are just those who present as pregnant.
CEO Kerry Anthony said: "It's appalling to see a woman go into labour in a one night only hostel, to then go into hospital and to not know where she can come back to.
"Women are coming in at 6pm or 7pm and having to leave again the next morning and walk the streets. We are trying to make sure that we are providing women with clinical support and getting them linked in with a GP," she added.
There are no national figures available for the number of newborn babies who leave hospital to live in homeless accommodation.
The Department of Housing, the Health Service Executive and the Dublin Region Homeless Executive have all confirmed that the number of children in such circumstances is not being collated at a national level.
In a statement, the DRHE said there is a "collaborative support system in place involving homeless services and health and family support services.
"There are a range of specific supported temporary accommodation and family hub type facilities for women with children, including newborns.
"All new mothers are contacted by the public health nurse following the birth of the baby," it added.
In a statement, the #mynameis campaign, which raises awareness of child homelessness, criticised the absence of national figures.
"We have spoken about the indignity of treating children as just statistics but it appears that newborns born into homelessness are not even making it as far as a statistic.
"The State is effectively turning a blind eye to thousands of children," it added.
Public Health Nurses have warned that temporary homeless accommodation is undermining the health of newborn babies.
One of the areas most affected by homelessness is Dublin North Central. The local HSE office confirmed that 18 children were born into homelessness in the area in 2017. An additional five were made homeless in the first year of their life.
Angela Kennedy, Director of Public Health Nursing in Dublin North Central, said: "The biggest challenge is around keeping track of families and their movements. Follow up is very difficult for these families.
"Everyone is trying to do the best they can but despite that, there are children falling through the cracks. It is the children who are extra vulnerable where there are child protection issues, where trying to trace them is difficult," she added.
Cork-based Public Health Nursing Consultant Patricia O'Dwyer said nurses go to extraordinary lengths to track families who have moved.
"We are so keen to stress the importance of intervening early in children's lives. These are lost opportunities."
Ms O'Dwyer also warned that living conditions were presenting issues for families and for public health nurses.
"I am aware of a family that was living in accommodation where the facility for re-heating bottles was on the ground floor. The mother, who had a newborn baby, showed her two year-old how to go down the stairs to pick up what was required. There are child protection issues there. It is far from ideal to be sending toddlers downstairs alone."