Continued pressure to back abortion would force doctors, nurses and other medical professionals out of medicine and add to "the staffing crisis already crippling the health service," Hayes predicted.
Hayes is one of several consultant colleagues at St. Luke's who have told management they would not perform abortions. He told that rally that abortion is "a procedure that helps no one and takes the life of the child ... Abortion is not life-saving, it's life-ending. It's not health care, and no amount of spin can make it health care."
The health department's documents show that "it is unlikely" that abortion service will begin at St. Luke's General Hospital in 2019.
In May, the Irish bishops' conference objected to job requirements mandating that certain consultant doctors be willing to participate in abortions, saying the country's abortion law had promised to safeguard conscience rights for medical professionals.
An advertisement for two consultants, for obstetrics/gynecology and anesthesia, at the National Maternity Hospital in Dublin says applicants must be willing to participate in abortions.
"This precondition runs totally counter to a doctor's constitutional and human right to freedom of conscience," said the bishops.
The bishops' conference said such preconditions may rule out the best possible person for the job by eliminating candidates solely because they are unwilling to perform abortions.
"A doctor who is eminently qualified to work as a consultant in these fields is denied employment in these roles because of his/her conscience," said the bishops.
"Doctors who are pro-life and who may have spent over a decade training in these areas and who may otherwise be the best candidate for these positions are now advised that, should they apply, they would not be eligible for consideration," they said.
A spokesman for the National Maternity Hospital argued that the specific posts were funded by the HSE for the purpose of abortions.
"They are therefore for individuals willing to contribute to the provision of these services. Other past and future posts are not affected. The conscientious objection guidelines for staff in both hospitals remain unchanged," the spokesman said, according to RTE.
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At least 640 general practitioners in Ireland signed a petition in November objecting to the new obligation of referring patients to other doctors for abortions.
The majority of the country's 2,500 GPs are unwilling to perform abortions. Only between 4 and 6 percent of GPs have said they would participate in the procedure.
At the July 6 All Ireland Rally for Life, Archbishop Eamon Martin of Armagh, said: "I march today because I believe it remains as important as ever to affirm the sanctity of all human life. The direct and intentional taking of the life of any innocent human being is always gravely wrong – we must avoid becoming desensitized to the value of every human life."
He called for more help for vulnerable women, for mothers and fathers who are in crisis, and for "parents who feel that they have made the wrong choice in having an abortion."