The procedure was done on a patient whose twin 18-week-old fetuses were not considered viable and who put the mother's life at risk, The Irish Times reported Friday.
The termination, which occurred several weeks ago, took place at the National Maternity Hospital, one of 25 hospitals in the country authorized to do abortions under the act.
The law required the woman's obstetrician and another doctor to certify the abortion was necessary because there was real and substantial risk to the mother's life.
An official of the facility said the hospital would have performed the abortion even before the law "where the prognosis is very poor," The Guardian reported.
"What's changed " the official said, "is that we can do our work in the best interests of the patient without fear of a possible Medical Council case."
The hospital is required by the law, known as the Protection of Life During Pregnancy Act, to furnish Ireland's health minister with the registration numbers of the doctors who did the abortion and those who were involved in certifying the procedure met the provisions of the law.
The health minister is required to publish a yearly report of the number of terminations performed under the law.