Taoiseach Micheál Martin has said the lack of official maternity leave for women politicians "doesn't reflect well on a modern democracy" and should be rectified.
He said the introduction of a proper system of maternity leave for TDs and senators could require a referendum.
The issue has been back on the agenda since Justice Minister Helen McEntee confirmed she is pregnant.
Mr Martin said the Government has yet to decide on the arrangements on her plans to take leave.
Asked if there would be a substitute minister during that time, he said: "We haven't got that quite worked out yet."
There have been efforts in recent years to legislate for a formal maternity leave system for politicians.
A bill to allow Oireachtas members to take up to 26 weeks' maternity leave was put forward by Fianna Fáil TDs Anne Rabbitte and Niamh Smyth.
The then minority Government led by Fine Gael supported it in principle, but identified a number of issues that would have to be addressed.
The bill lapsed with the dissolution of the last Dáil in January.
Mr Martin asked about the issue of maternity leave for politicians during a pre-Christmas round-table interview with journalists.
He said: "It may very well require a referendum and perhaps should and there will be discussions on the matter with the Attorney General.
"There are issues there, of a constitutional nature, in terms of a member of the house. For example, as a TD or senator and as a minister."
But he added: "I think it doesn't reflect well on a modern democracy that we cannot facilitate a woman going on maternity leave in ministerial office.
"I think that's something we should rectify. The precise mechanisms to rectify that we are still examining.
"We will have to do some interim measures.
"I'm not talking just in the context of Helen McEntee, because Helen herself would want us to do it generally as a basic, necessary modern reform of our parliamentary democracy."
Mr Martin suggested that any reforms should cover paternity leave as well.