Over 270 complaints into pre-school services were investigated by the Child and Family Agency Tusla last year.
Its Early Years Inspectorate Annual Report shows a total of 2,033 inspections were carried out.
The most common area of complaint referred to the health, welfare, and development of a child.
The report outlined that there were 204 incidents notified to Tusla.
On one occasion, a child's hand was accidentally pierced with another child's Epipen.
Another incident saw a child break their femur after falling off a slide.
There were also 11 instances where a child went missing.
Of the overall number, 64% (131 cases) related to a serious injury to a pre-school child which required immediate medical treatment.
Percentage of incidents notified by region | Source: Tusla
Almost 4,500 early years services were registered nationally at the end of 2017, including 96 newly-approved services.
More than 90% of services assessed under regulations relating to premises, staffing levels, and first aid were reported to be compliant.
But 55% of services were compliant regarding safeguarding health, safety and welfare of a child.