Update 5.38pm:The March for Choice is the first major demonstration since the Government set an indicative timescale of early summer 2018 for a referendum on the section of the state's constitution that ensures tight legal restrictions on terminations.
Campaigners gathered at Parnell Square from lunchtime before making their way down the city's main thoroughfare, O'Connell Street.
Chanting and waving placards, demonstrators then marched along the River Liffey past the landmark Custom House before crossing the water on their way to the gates of the Irish parliament.
Anti-abortion activists staged counter events in the city and across Ireland to warn against relaxation of the current law.
The existing Eighth Amendment of Ireland's constitution affords equal rights to pregnant women and unborn children. Added to the constitution in 1983, the amendment recognises an unborn child's right to life.
Earlier: The Pro Life Campaign (PLC) has said there is no real difference between “partial” or “full” repeal of the 8th Amendment.
The campaign says either otion would "strip unborn babies of all meaningful protections under the law".
PLC spokesperson Dr Ruth Cullen made her remarks at an awareness event in Grafton Street earlier today in advance of today’s ‘March for Choice’ in Dublin. The PLC is also holding similar events in 21 locations throughout the country today, where volunteers will distribute literature to members of the public.
Dr Cullen said: “There is much speculation at present about whether any referendum proposal would be ‘restrictive’ or allow abortion in wide-ranging circumstances.
“In reality any form of repeal would deliver the same result – an abortion regime in Ireland, where it would become impossible to have any meaningful protections for unborn babies.
"Legalised abortion is public policy in defiance of science. We either protect every human life in our laws or we end up protecting no one. Once it is conceded that unborn babies are unworthy of legal protection in some situations, it is in effect saying that no unborn babies have any intrinsic value.
“It might be popular with some to attack the 8th Amendment at every turn and overlook all the good it has done for this country. But the fact is there are thousands of people alive today in Ireland thanks to the 8th Amendment. That’s something we should celebrate and cherish, not denigrate.
"I am confident support for full retention of the 8th Amendment will grow and grow as people realise what the alternative would entail and the countless innocent lives that would be lost through abortion.”
Earlier: Thousands of people are expected on the streets of Dublin later to call for change to our abortion laws.
The March for Choice is the first major rally since the Government set an indicative timescale of early summer 2018 for a referendum on the 8th Amendment.
The existing Eighth Amendment of the constitution affords equal rights to pregnant women and unborn children. Added to the constitution in 1983, the amendment recognises an unborn child's right to life.
Terminations are currently only permitted when the life of the mother is at risk and the maximum penalty for accessing an illegal abortion in Ireland is 14 years in prison.
With the prospect of a referendum having been on the horizon for some time, pro-choice and anti-abortion advocates have already been long campaigning on the issue. Those efforts are set to intensify now that a time frame has been set for the vote.
The rally in Dublin is the first big set-piece since Taoiseach Leo Varadkar announced on Tuesday that a referendum will likely be called in May or June next year. Counter protests are expected.
Today's rally will assemble at the Garden of Remembrance on Parnell Square from 1.30pm, before marching on Dáil Éireann at 2pm.
A pro-choice rally is also planned outside the Irish Embassy in London today.
Meanwhile, the Pro Life Campaign is holding an awareness event at the bottom of Grafton Street (at junction with Suffolk Street) at 1pm today. Similar events will be held at 21 locations throughout the country during the day, where volunteers of the Pro Life Campaign will distribute literature to members of the public.
A parliamentary body has been established to advise on wording for the referendum.
The Committee on the Eighth Amendment of the Constitution is considering a report from Judge Mary Laffoy, who chaired a specially-designed Citizens Assembly of 99 people who deliberated and voted on the issue.
The assembly called for article 40.3.3, which was altered under the Eighth Amendment, to be removed from the Constitution.
It said it should be replaced by a provision which placed the onus on politicians to pass laws on termination of pregnancy, rights of the unborn and pregnant women's rights.