Allen, 28, has been attending the March since she was a teenager, almost from the year of the first March in 1997.

“It’s the most important cause out there,” said the former Campaign Life Coalition delegate to the United Nations, “to stand as a witness, as a voice for the unborn.”

On May 14, 1969, Parliament passed Trudeau’s bill, amending the Criminal Code to decriminalize homosexuality, make divorce easier and allow women to get an abortion if a committee of three doctors ruled pregnancy endangered a women’s mental, emotional or physical well-being.

 Campaign Life Coalition, a national pro-life group, started the March to shed a national spotlight on the issue and call for a law to ban abortion. This year’s campaign is called “Exodus 2009: A future without abortion.”

 Jim Hughes, the coalition’s national president, said the March highlights the importance of human rights, from conception to natural death.

Since 1992 there have been approximately 100,000 abortions per year in Canada, according to Statistics Canada. Campaign Life Coalition estimates 3.5 million abortions have taken place since 1969.

The three-day event, expected to draw more than 10,000 participants, will start with a May 13 Mass at St. Theresa parish, followed by a candlelight vigil at the Canadian Tribute to Human Rights Monument. On May 14, Masses are scheduled at Notre Dame Cathedral and St. Patrick’s Basilica, and there will be a prayer service at St. George Anglican Church.

The May 14 March and rally on Parliament Hill is expected to be attended by several politicians, including Conservative MP Rod Bruinooge and Liberal MP Paul Szabo. Several bishops, including Toronto Archbishop Thomas Collins, Ottawa Archbishop Terrence Prendergast, London Bishop Ronald Fabbro and Peterborough Bishop Nicola De Angelis, are scheduled to attend.

The event will end with a May 15 youth gathering.

“It’s important to let politicians know that abortion is not a medical necessity but is tragically being used as a violent form of birth control,” said Denise Mountenay, founder of Canada Silent No More.

Before converting to Christianity, Mountenay said having three abortions before the age of 30 scarred her physically, emotionally and spiritually. The experience of “not being told the truth” by her doctors about the physical risks of abortion, she said, motivated her to start the organization.

For pro-life supporters, abortion isn’t just a “woman’s issue.”

Our Lady Seat of Wisdom Academy professor John Paul Meenan has been attending the March for the past 11 years.  Although yearly marches haven’t led to a law banning abortion, Meenan said he remains hopeful that change can happen.

Keri-Lee Mullan, vice-principal at Toronto’s De La Salle College, plans to attend with six students. Mullan, 33, is four months pregnant and says being at the event will serve as an “important witness.”

While pro-abortion advocates argue they’re giving women a choice, Mullan said the March presents a sober message.

“Abortion kills children and is killing Canadians,” she said.