The Coalition of Mother and Baby home Survivors has claimed that up to 7000 babies could have been buried at 9 mother and baby homes across the country.
Chairperson Paul Redmond has said the worst is yet to come.
"Tuam is the tip of the ice-berg. It was the fifth biggest of the Mother and Baby homes and some of them like St Patrick's on the Navan road were four times the size.
"It's a fact that the further back you go, the worse the conditions got.
"St Patrick's was operating from 1904, 21 years before Tuam even opened."
A senior Government Minister has described the Galway mother and baby home scandal as nothing less than gruesome.
Leo Varadkar says the Commission of Investigation needs to continue its work, as so many questions remain unanswered.
"Ireland in the 20s, 30s, 40s, 50s was a very different place to what it is now," he said.
"But even by the standards of the time it is abhorrent to me that children weren't given a proper Christian burial.
"You would have expected at the very least a religious order would have insured they were treated with dignity in death and that didn't happen."