Kerry Gardaí are investigating an incident involving a pregnant woman and a man in his 20s.
A woman who was 32 weeks pregnant suffered multiple injuries in the attack, which happened at a house in Listowel.
The woman, believed to be in her 30s, delivered her baby in the immediate hours after the horrific incident.
According to the Irish Independent, the infant girl was stillborn.
As the woman was being treated at University Hospital Kerry, a man in his 20s was arrested at a nearby address.
He has been detained and will face questioning about the serious assault.
The nature of the Garda investigation will be determined by the results of the post mortem examination, which will be carried out this week.
"Following the stillbirth of a baby the local Coroner and Office of the State Pathologist were notified. A post-mortem is expected to take place on Wednesday (27/6/2018). The results of the post-mortem will determine the course of the Garda investigation into this matter," Gardaí said in a statement.
"No further information is available at this time. Enquiries are ongoing."