The billboards feature the words “one of us” and, according to the institute, show how “unmistakably the baby in the womb is a fellow human being”.
The campaign is funded by the institute at a cost of €20,000.
Speaking on behalf of the Christian think tank and advocacy group, Maria Steen said when the issue of abortion is being discussed, both mother and child need to be taken into account: “We have launched this campaign because those who want to repeal the pro-life amendment constantly ignore or downplay the fact that abortion always ends the life of the child in the womb.
“The pro-life amendment protects all human life, beginning at conception.
“It recognises that the baby in the womb is a member of the human family. It is one of us. This is something pro-choice campaigners have to either deny or pretend does not really matter.”
Ms Steens said it is “extremely noticeable” neither the Citizens’ Assembly nor the joint Oireachtas committee on the Eighth Amendment of the Constitution showed images of the baby in the womb at its various stages of development.
“The unborn child was essentially invisible.”
Ms Steen also said it can not be denied the victim of an abortion is a human being
“In addition, if the Eighth Amendment is repealed, the law on abortion can subsequently become anything. The initial law, however permissive it may be, is only the starting point.
“Our poster campaign is doing what the Citizens’ Assembly and the joint committee would not do. It is making the unborn child properly visible in all its obvious humanity.
“It is undeniably ‘one of us’ and when enough Irish people see this, we are confident that they will vote to retain a provision that protects every human life, born and unborn, female and male.”
The Iona Institute’s billboard campaign was welcomed by the Save the 8th group, which itself launched a national billboard campaign a number of weeks ago.
Its spokeswoman Niamh Uí Bhrian said the voice of the child in the womb has not been heard in the debate.
“We are very pleased that Iona is putting the focus of the debate squarely where it belongs.
“In this debate, we will hear countless abortion stories from pro-repeal campaigners.
“Over the coming months, pro-life organisations will be reminding the public of a salient fact that has been ignored in this debate: Babies have abortion stories too.”