You may know that various United Nations documents defend unborn life. The 1959 Declaration of the Rights of the Child includes: "the child, by reason of his physical and mental immaturity, needs special safeguards and care, including appropriate legal protection, before as well as after birth". You can read more about how international conventions protect the unborn in What rights, if any, do the unborn have under international law? by Doctors John Fleming and Michael Hains on the Priests for Life website.
I mention such global agreements because another such document is being cited in the matter of the Australian state of Victoria's Abortion Law Reform Act. Our colleagues at New South Wales Right to Life describe how this law would force health workers to declare their opposition to abortion and to refer women who want abortions to people who will perform them. Lawyers point out that agreements which Australia has signed could invalidate this measure. Pursuing sources which NSW Right to Life use, we find that the 1966 International Covenant on Civil and Political Rights states: "No one shall be subject to coercion which would impair his freedom to have or to adopt a religion or belief of his choice." In a comment on that covenant, the UN's human rights commissioner points out that that document's provisions mean that "no one can be compelled to reveal his thoughts or adherence to a religion or belief."
In other words, not only are healthcare workers entitled to their beliefs (including an objection to abortion), but forcing them to declare such beliefs is against international agreements. Meanwhile, abortion supporters want abortion made an international human right.