Ireland's current abortion laws ban all terminations except in cases where the mother's life is at risk.
Draft legislation already prepared in case of a pro-choice vote in Friday's historic referendum would legalise abortions in the first 12 weeks of pregnancy and up to 24 weeks for health reasons.
Here is a rundown of the main legislative points.
- What the law says -
The eighth amendment to the Irish constitution, introduced by referendum in 1983, "acknowledges the right to life of the unborn". It forbids abortions, even in cases of rape, incest or where the foetus is malformed. The penalty is 14 years' imprisonment and a fine.
In 2012 the death of Savita Halappanavar, a 31-year-old who died of sepsis after a miscarriage when she was denied a medical abortion, outraged public opinion and led to a change in the law.
The following year an exception was introduced to the amendment, authorising abortion in cases where there was a mortal risk to the mother, including the risk of suicide. Under this provision 26 abortions were performed in Ireland in 2014, 26 in 2015 and 25 in 2016.
- Abortions abroad -
The 13th amendment of the Irish constitution guarantees an individual "freedom to travel" to other states.
More than 168,000 women used this freedom to visit hospitals in England and Wales for abortions between 1980 and 2016, according to British Department of Health statistics compiled by the Irish Family Planning Association. By these figures, around 13 women who give Irish home addresses have abortions in England and Wales every day.
In 2011 Irish citizen Amanda Mellet was forced to travel to the city of Liverpool in the north of England to have an abortion when it was discovered the foetus of her child was mortally deformed.
Doctors reportedly told her the infant would be born dead or die shortly thereafter.
Considering herself to be a victim of unfair Irish legislation, she took her case to the United Nations Human Rights Committee which agreed she was subjected to "cruel, inhuman or degrading treatment".
Dublin paid her 30,000 euros ($35,000) in compensation.
- Information on abortion -
Spreading information on how to acquire an abortion is also strictly controlled in Ireland.
Following the approval of the eighth amendment, Irish courts initially forbade agencies from helping women in their efforts to organise abortions abroad.
But the 14th amendment, voted in by a 1992 referendum, guaranteed the right of an individual to obtain "information relating to services lawfully available in another state".
However this right was strictly framed by the Regulation of Information Act, adopted in 1995.
This law, among other things, forbids individuals to "advocate or promote" the termination of a pregnancy using "services outside the state".
The act also obliges professionals giving advice to women about abortion to make them aware of all alternatives, encompassing scenarios such as adoption at birth.
- Plans for reform -
On Friday, Irish voters will be invited to choose whether or not to remove the eighth amendment and replace it with the phrase "provision may be made by law for the regulation of termination of pregnancies".
If the pro-choice vote wins, the government will be tasked with drafting fresh legislation which, if it is passed by parliament, should legalise abortions during the first 12 weeks of a pregnancy and up until 24 weeks for reasons of health.