Senators Fidelma Healy Eames and Paul Bradford have lost the Fine Gael party whip after voting against the proposed abortion law.
The Protection of Life During Pregnancy Bill this evening passed its first Seanad vote by 41 votes to 15.
The legislation will go to committee stage in the upper house tomorrow.
The votes of Healy Eames and Paul Bradford mean Fine Gael has now lost seven members who voted against the bill.
Senator Healy Eames said she had been a member of Fine Gael for many years and the party had made a "solemn promise" to the electorate not to legislate for abortion.
Paul Bradford said the proposed law ran contrary to the fabric of Fine Gael.
Senator Bradford is married to former European Affairs Minister Lucinda Creighton, who last week lost the Fine Gael party whip when she voted against the bill in the Dail.
Fianna Fáil Senator Averil Power, who voted for the bill today, said she had some difficulty in making her decision.
Senator Power, who was adopted as a baby, said she would never support abortion on demand, but would be voting in favour of the legislation.