RTE says it will not be replacing Claire Byrne on Prime Time during her maternity leave.
Instead, the station's flagship current affairs programme will use staff Katie Hannon and Robert Shortt and other reporters to host discussions with guests in studio.
"There will be no fixed replacement for Claire Byrne on Prime Time. In her absence the presenting work will be spread across existing staff on the show," an RTE spokeswoman said.
It declined to give the date from which Byrne, who is expecting her first baby in October, will take her maternity leave.
"We don't want something which could turn into a royal babywatch. That is why there will be no comments as regards Claire's maternity leave," said an RTE insider.
However, with Prime Time ending this week, and off-air throughout August, this changeover will not take place until the series returns this September.
Despite Prime Time being off air for a month, the station said that researchers would continue to work on a range of stories and could be brought back at short notice should there be any major developments.
"Prime Time will of course go on-air for any significant stories. The programme will take a short break for a few weeks in August but work will continue behind the scenes, especially around investigative programming," said an RTE spokeswoman.
And although the new Prime Time set would not be used during the month-long break, RTE stressed the studio space would continue to be used in a "cost-effective way".
Pat Kenny, one of the show's hosts, predicted Prime Time woyuld undergo more changes on its return.
Thrown by the fall-out from the Father Kevin Reynolds case, it has won back respect, with plaudits for reports by the RTE investigations Unit, broadcast in the Prime Time slot, on how gangs are preying on clothes donated to charities, the Bethany Home scandal, and childcare in Ireland.