First Communions in the Catholic Diocese of Derry will not now take place until September.
In a letter to priests, the Bishop of Derry, Donal McKeown said he had made the decision to postpone the services on account of parties and other socialising following the First Communions which could assist in the transmission of Covid-19.
In the letter, reported by the BBC, Bishop Donal said the diocese's parishes in Northern Ireland are "safe places for the celebration of First Communion and Confirmation".
"However, I am concerned about the parties and other socialising which, although completely disconnected from the celebration of the sacraments and the environs of the church, can and often do occur," he added.
Bishop McKeown added that postponing communion services had not been an easy decision to take:
"I do not take this decision lightly, but I am conscious that we must do everything we can to ensure that life is protected in the midst of this pandemic, noting that there has been some upturn in case numbers locally in recent days," he said.
Bishop McKeown announced confirmations will take place in June, while baptisms will be limited to a maximum of 25 people.
Public worship at Catholic Churches is due to resume in Northern Ireland on Friday. However, the Church of Ireland, Methodist and Presbyterian Churches in Northern Ireland won't resume in-person services until Good Friday.
First Communion is usually celebrated during April and May for children aged between seven and eight.