Former justice minister Nora Owen has said she does not believe the public would be "thankful" if a new minister were to be appointed to replace the current Justice Minister when she has her baby.
The former Fine Gael politician said Helen McEntee will face criticism from the public for taking leave, despite being entitled to take time to take care of her child.
She added that Ms McEntee's upcoming absence would be "giving somebody, somewhere, a lot of headaches".
Mrs Owen also said it was "extraordinary" that it appeared a constitutional amendment is needed to ensure public representatives, including Ms McEntee, are permitted to take maternity leave.
Ms McEntee will become the first Cabinet minister to give birth while in office. The baby is due in May and Ms McEntee intends on taking six months' leave.
At present, public office holders have to claim sick leave when they take time off to have and look after their newborn baby.
Mrs Owen, who was justice minister between 1994 and 1997, told the PA news agency: "It does raise the whole issue of what happens when somebody like Helen [McEntee] goes and says she's going to take her full six months.
"Do you raise the profile of a junior minister and put them into a senior ministry? Do they get the extra money because they are on less pay? And then do you appointment a temporary Junior minister?"
She added: "I don't think the public would be thankful, I think, for kind of a full new minister to be appointed on the full salary at a time when people are really struggling.
"I'd imagine that is an area that is giving somebody, somewhere, a lot of headaches."
She added: "I admire her [Ms McEntee] because she will get criticism.
"Someone will say: 'Oh, she's getting her salary, she should be in there'. She will get her salary the same as anybody else on leave when they're out."
Mrs Owen said it was a "pity" that a referendum may be needed before women TDs, senators and councillors are given maternity rights, and that it "worries" her that more women are not entering political life.
She admitted she had been targeted for being a woman during her two-decade-long career in the Dail and described the online abuse of female politicians as "disgraceful", saying it "shouldn't be happening".
"Very often, depending on what ministry you have, as a woman there can be an element of targeting," she added.
"I remember one journalist. He's dead now, so I'm not maligning him. It was a particularly difficult time and there was lot of crime and drugs were growing.
"He wrote an article saying: 'We probably wouldn't be going through this now if Michael Noonan had been made Minister for Justice as opposed to Nora Owen'.
"A man in other words. When someone used to raise it with me I used to joke and say: 'Oh yeah, the criminals are all sitting around saying: 'Come on, lads, let's do the crime now because there's a woman in there and we won't get caught'.
"It was such a stupid thing to say, and to be honest, a very misogynistic thing to say because, I mean, crime is crime.
"Up until Maire Geoghegan-Quinn, every minister of justice before that was a man. And our prisons didn't empty. Our crime didn't stop ... That kind of thing really angered me but you learn how to cope with it."
Mrs Owen features in Proud to Serve: The Voices of the Women of Cumann na nGaedheal and Fine Gael 1922-1992.
Fine Gael is marking International Women's Day by launching a reprint of the book by Maria Hegarty and Martina Murray.
A grandniece of Michael Collins, Mrs Owen was elected to Dail Eireann in 1981 and served as a TD for Dublin North for two decades.
When she was first elected to the Dail she had three small children and was one of only a handful of female TDs.
In the book she recounts how after winning her first seat in 1981 a journalist was overheard reading out his article as he called his newspaper: "An anonymous suburban housewife has just had a surprise victory in Dublin North."
She said she had to deal with men referring to her as a housewife throughout her career, using it as a "way to put people down or put them back in their box".
She also said she had been left "seething" on numerous occasions as male TDs passed off her ideas as their own.