Ireland was once considered the most Catholic country in the world. A place where 90 per cent of the population attended mass, and where divorce, contraception and abortion were forbidden.

But in recent years the country has become increasingly secular. In 2015, a referendum passed endorsing same-sex marriage and another vote this week could liberalise its strict abortion laws.

On May 25 Irish voters will decide whether they want to repeal the Eighth Amendment of Ireland's constitution which protects the right to life of the unborn. It means an abortion can only be carried out if the mother's life is at risk.

Photo: Some in the No campaign fear Facebook's ban on foreign ads will hurt them more than the Yes campaign. (ABC News: David Sciasci)

Even in cases of rape, child sexual abuse and incest, or where fatal foetal abnormalities are present, a woman can't access a termination.

The push for a referendum was sparked in 2012 by the horrific death of Savita Halappanavar. The 31-year-old dentist had a septic miscarriage after being denied an abortion.

The Indian-born woman had been told by hospital staff she could not have an abortion because Ireland was a Catholic country.

'I felt dirty and ashamed'

The abortion debate is deeply personal for many voters. Each year over 3000 Irish women and girls travel to the UK to get a termination.

Lucy Watmough was single and on the pill when she fell pregnant in 2015. She says she was too young for motherhood and not financially stable enough to provide for a child.

"I travelled to London by myself. I flew over on an early morning flight. I couldn't be fully anesthetised because I had to fly home the same day, so I was awake through the whole procedure," she said.

"Afterwards all the other girls there went home to their own beds. I went to the train station and I stood on a train for about 40 minutes or an hour, bleeding on the way back to the airport because there were no seats for me to sit on. Then I waited in an airport for hours so I could fly home.

"I think the stigma was the real problem for me, aside from the trauma of having to travel. I didn't tell anybody for months afterwards. I felt dirty and I felt ashamed."

Ms Watmough has been urging friends and family to vote yes.

"The Eighth Amendment does not stop abortion happening in Ireland. It just makes it unsafe. We're just showing a complete lack of compassion and care for our own women," she said.

"It's the most important thing in the world to me right now that this passes, so that one day when I have a daughter, she won't go through what I went through. That she will grow up in a world, in a country where she has autonomy over her body."

'They couldn't end my life'

The No campaign also has its advocates who will be voting for deeply personal reasons.

Gavin Boyne is a first-year philosophy student at Trinity College in Dublin. His mother was just 16 when she fell pregnant. He says he is alive because of the Eighth Amendment.

"Twenty years ago, my mother was in England as per the request of my grandparents and she was there to have an abortion," he said.

"Three weeks had passed and in those three weeks my grandparents were thinking, well, what are we doing here? And the only reason they came to that deliberation was because abortion was illegal in Ireland.

"What they found was the Eighth Amendment, which indiscriminately protects unborn children and gives them the right to life. So, they came to the conclusion that I was a human being, a unique human being with value, and they couldn't end my life.