"I have been a committed member of Fine Gael for many years - the party that made a solemn promise to voters not to legislate for abortion," she said.
"It saddens me greatly that Fine Gael has broken this promise. In the words of Thomas More, any public servant who would forsake his private conscience for the sake of his public duties leads his country down the short route to chaos."
The legislation was drawn up following the death of Savita Halappanavar, an Indian dentist who died in an Irish 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".
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.
