The annual pro-life march occurred a day after Liberal leader Justin Trudeau said pro-life supporters would be banned from running for office as candidates of the Liberal party.
But it was the Pope's message that was read aloud to an enthusiastic, peaceful crowd that organizers projected would top 20,000. Sent from the office of the Vatican Secretary of State Pietro Parolin, the Pope offered his support and prayers.
"His Holiness Pope Francis is pleased to greet everyone taking part in the 17th National March for Life in Ottawa, and he assures them of his spiritual closeness as they give witness to the God-given dignity, beauty and value of human life," the message read.
"He prays that this event foster greater respect for the inviolable right to life of each person from conception to natural death, and support the efforts of all who labour to ensure that this fundamental human right receives adequate legal protection.
"To the organizers and participants, and in particular to those who aid women in crisis pregnancies and their children, the Holy Father cordially imparts his Apostolic Blessing as a pledge of joy and peace in the risen Lord."
The Pope sent similar messages in recent weeks to March for Life events in Rome and Washington.
A day earlier, Trudeau told reporters that he intends to make the Liberal party "resolutely pro-choice." All future candidates will be vetted during the nomination process to ensure that only those who are pro-choice will be permitted to stand for the Liberal party in elections.
“It’s not for any government to legislate what happens, what a woman chooses to do with her body, and that is the bottom line,” Trudeau was widely quoted. “I have made it clear that future candidates need to be completely understanding that they will be expected to vote pro-choice on any bills.”
In past years, the March for Life was always attended by some Liberal MPs who opposed abortion. Trudeau said that current Liberal MPs will be "grandfathered" in and allowed to continue to stand for election. But others will be vetted and, despite earlier promises to guarantee open nominations, Trudeau now says only approved candidates will be permitted to enter the nomination races.