The controversial new laws go to a final vote on Wednesday night.
The predominantly Catholic nation's abortion laws faced global scrutiny after the death of 31-year-old Indian woman Savita Halappanavar in a Galway hospital last October.
The Bill follows a 2010 European Court of Human Rights ruling that found Ireland failed to implement properly the constitutional right to abortion where a woman's life is at risk.
Under a 1992 Supreme Court ruling, women in Ireland are legally entitled to an abortion if needed to save a mother's life – but legislation has never been passed to reflect this.
The Protection of Life During Pregnancy Bill allows for abortion in circumstances where doctors certify there is a real and substantial risk to the life of the mother.
The new Bill also permits a termination when one obstetrician and two psychiatrists unanimously agree that an expectant mother is a suicide risk.
The "suicide clause" has caused consternation among some lawmakers who believe it will be abused and lead to more abortions in Ireland.
Voting against the Bill
Four government deputies voted against the Bill at an earlier stage and were expelled from the parliamentary party as prime minister and Fine Gael party leader Enda Kenny has not allowed a free vote on the matter.
A number of other lawmakers and possibly a member of Kenny's Cabinet, Lucinda Creighton, junior minister with responsibility for European Affairs, are likely to vote against the Bill.
Lawmakers will spend Wednesday discussing 165 amendments tabled in the past few days, but widespread changes as demanded by some are unlikely to be introduced.
The case of Halappanavar highlighted the problematic legal situation in Ireland regarding abortion.
She had sought a termination when told she was miscarrying, but the request was refused as her life was not at risk at the time. She later died of sepsis days after miscarrying.
The Bill has caused intense debate with around 35 000 opponents attending a march in Dublin last Saturday.
Others argue that the Bill is too limited as it does not allow termination in cases of incest or rape, and fails to reflect the reality of thousands of Irish women who travel abroad every year to have an abortion. – AFP