Gardai are investigating "all the circumstances'" that led to a baby receiving critical injuries in Co Louth.
The infant, believed to be a nine-week-old girl, is fighting for her life in Temple Street Hospital in Dublin.
Gardai in Drogheda are looking into the case.
Irish Independent reporter, Robin Schiller, says they have held a case conference as part of their investigation.
He added that Gardai were alerted to the incident on Tuesday last.
"The child was rushed to Temple Street Children's Hospital where she remains in a critical condition," he said.
"Gardai are currently following a number of lines of inquiry."