A vote on the landmark laws, which enshrine a woman's right to a termination if her life is at risk, including from suicide, was expected to pass at around 5am on Thursday morning.
But as discussions rumbled into dawn with no sign of an end, the Dáil parliament was adjourned with plans for the debate to resume on Thursday.
The laws will be supported by the vast majority of the country's politicians, but they are likely to see the demise of a junior minister who has shown signs of joining a small backbench revolt.
Despite Minister for European Affairs Lucinda Creighton's rebellion, the laws are likely to pass comfortably with a large majority of the vote.
The Protection of Life During Pregnancy Bill 2013 was drawn up following the death of Savita Halappanavar, an Indian dentist who died in a Galway hospital in October last year after being denied an abortion as she miscarried 17 weeks into her pregnancy.
Her widower Praveen claimed the couple had been told a termination was not allowed because "Ireland is a Catholic country".
So fraught has debate around the legislation been that rebel members of Fine Gael, the senior coalition Government party, have been threatened with being barred from standing for the party at the next election.
Taoiseach Enda Kenny has stood firm on his hard line, insisting his members are well aware of the consequences of breaking ranks.
He said that the debate could run on until Friday, but that he did not want to extend the Dáil sessions until the end of July.
We had 21 years of inaction. What's going here is medical clarity and legal certainty for the women of our country who have had a constitutional right conferred upon them.
Taoiseach Enda Kenny
"The main issue of the question of suicide being an issue was dealt with last night because there was extensive debate on that last night," Mr Kenny added.
Six pro-choice TDs are to vote against the legislation, claiming it does not go far enough to protect the lives of women.
Richard Boyd Barrett, Clare Daly, Mick Wallace, Luke Ming Flanagan, Joe Higgins and Joan Collins have claimed the bill is unnecessarily restrictive and criticised the fact it seeks to criminalise women who have an unlawful abortion.
Dramatic scenes in the run-up to the monumental vote have been set against a backdrop of vigils outside Leinster House, where a group of pro-life activists prayed beside pro-choice campaigners waving placards with Mrs Halappanavar's face on them.
The suicide clause in the legislation has remained the most divisive aspect throughout.
Ms Creighton has refused to support the rule, which allows an expectant mother to seek an abortion on the grounds that she is prepared to take her own life and called for alternative therapies to be offered instead.
She lost the Fine Gael party whip on Thursday night and confirmed she would resign from her ministerial position after voting against the amendment.
She is the fifth Fine Gael TD to be expelled over the contentious legislation, after four colleagues voted against the Government in an earlier round of votes.
Hate mail and death threats to politicians, and intimidation of campaigners have raged throughout the divisive abortion debate.
The legislation follows a 1992 judgment by the Supreme Court in Dublin, known as the X case, where judges ruled that abortion should be allowed if there was a threat to the mother's life, including suicide.
The case was taken by a 14-year-old rape victim who became pregnant and was refused permission by Irish authorities to travel to the UK for an abortion.
Ireland was also under pressure after a European Court of Human Rights ruling that a woman in remission with cancer was discriminated against because she was forced to travel overseas for a termination.
The Fine Gael-Labour coalition Government is the first in the 21 years since the X case to attempt to pass legislation on abortion.
The catalyst for action was worldwide outcry over Mrs Halappanavar's death.
An inquiry found medics in University Hospital Galway missed an early opportunity to terminate her pregnancy on health grounds and unacceptable clinical practice.
The case sparked massive debate among obstetricians and politicians over whether the guidelines medics had been operating under were clear.
Previously, doctors based their decisions on advice from the Irish Medical Council and the X case.
Choice campaigners have continued to demand further action, claiming Ireland only exports its problem with about 4,000 women registering with an Irish address for an abortion in the UK every year.
Campaigners have also pressed for abortion to be allowed in other circumstances, such as fatal foetal abnormalities, but were told that it would not be included in any loosening of Ireland's strict regime.
Following the final vote by TDs, the bill will be considered by the Seanad - the upper house of parliament - where it will be passed.
After that, provided there are no demands for further amendments, the legislation will be brought to President Michael D Higgins who will sign off on it and enshrine it into Irish law.
The Government expects the law to be enacted before the Dáil breaks for summer on 18 July.
Meanwhile, a Labour politician Michael McNamara voted "incorrectly" on one amendment as debate on the legislation drew to a close.
The Dáil record cannot be changed but it is understood Mr McNamara will not face any sanction.