The Taoiseach, Mr Ahern, has said he has no doubt that if the referendum is defeated it will lead to a more liberal abortion regime in the long term.
He was speaking on the largest of the three Aran Islands, following the official opening of a new water scheme.
"To be fair to people who are against it, as they were in other countries, they would say in the short term, that wouldn't happen. But, over time, it has happened everywhere else. They would find it would be impossible to draw the line." He said 4½ years had been spent looking at the issue and it was clear, with the best intentions of having a restrictive abortion regime, that it was impossible to achieve.
He said the experience in Britain was one where people in the 50s and 60s believed legislation could provide a restrictive abortion regime. Now any woman could have an abortion up to six months, and if there was any abnormality an abortion could take place any time during the pregnancy.
"I do not think that is what people in this country would want and a No vote will ultimately lead to that. It won't happen in the morning but it will happen over a period of time and that is why I believe the Protection of Human Life in Pregnancy Bill is a good Bill. It's a balanced Bill."
It was not based on a political assessment of abortion, he added. The obstetricians, the gynaecologists, the masters of the hospitals, and the main professorial units of the psychiatry profession were all on the Yes side.
Asked about the problem of 7,000 women travelling to Britain for abortions every year, he said he was trying to deal with the laws in this State. "I think there is widespread support for the initiative we have down for people who do have to travel." The solution for women in crisis pregnancies was to provide them with counselling, not to find them somewhere to find an abortion, he said.
He was hopeful that the referendum would be carried, following an opinion poll which shows that many people are undecided. It was still the intention to hold the general election in May, he added.
The referendum poll on Inis Mór takes place on Monday. Islanders believe there will be a low turnout. One resident, Mr Michael Flaherty, said many people were undecided.