The Dáil has passed the second stage of the Protection of Life During Pregnancy Bill by 138 votes to 24.
The bill now proceeds to committee stage.
Four Fine Gael TDs - Billy Timmins, Peter Mathews, Brian Walsh and Terence Flanagan - voted against the bill.
The four Fine Gael deputies were joined in the no lobbies by former Labour TD Colm Keaveney and Sinn Fein’s Peadar Tóibín.
Fianna Fáil TDs voted decisively against the measure with 13 rejecting the bill and only six in favour
Those supporting the measure were Micheál Martin, Michael Moynihan, Barry Cowen, Billy Kelleher, Timmy Dooley and Niall Collins.
A Fine Gael spokesman has confirmed that the four TDs who voted against the Protection of Life During Pregnancy Bill are immediately and automatically expelled from the parliamentary party.
They are also likely in coming days to be removed from Oireachtas committees on which they sit.
Minister of State Lucinda Creighton voted with the bill.
Billy Timmins told RTÉ he was aware of the consequences and was prepared to accept them - and he considered loss of the party whip "a small price to pay."
He said he never thought he would lose the party whip of Fine Gael because he wouldn't support a bill to legalise abortion in this country.
He said he was not aligned to any group, but had reached his decision as an individual, and he didn't know if other Fine Gael TDs would vote against the Report or Final stages of the bill.
Mr Timmins said the legislation was not evidence-based, and that if passed it would only be the beginning of the trouble over the issue, not the end.
In a statement, Peadar Tóibín said: "Its is with great sadness that I have had to separate from my party on this but I cannot vote for a medical evidence free bill that will result in the death and disablement of children.
"I am committed fully to the republican project of unity equality and prosperity and I hope that I get an opportunity to put my energies into the republican project again."
Health minister warns of doctor "witch hunt"
Minister for Health James Reilly told the health sub-committee there will be a monthly notification process on the number of terminations under the Protection of Life During Pregnancy Bill.
James Reilly told Fine Gael’s Peter Fitzpatrick that the number of terminations and the heading under which they occurred - such as physical illness, emergency illness or suicidal ideation - will be published.
However, he said the names of the doctors will not be made public because it will lead to a "witch hunt of doctors.”