Politicians, activists and others who want to see limits on abortion are using new arguments to make their case, adopting language usually used by human rights advocates.

Terms like "gendercide" — aborting female fetuses in the hope of having male children instead — and "pre-born rights," as well as stories of women who say they were coerced into ending their pregnancies, are framing the argument against abortion as a human rights issue.

Thousands of protesters were on Parliament Hill Thursday for an annual anti-abortion rally, pledging to keep up their fight to end abortion in Canada.

The March for Life protesters arrived on the Hill weeks after Conservative backbenchers said they weren't allowed to talk about abortion in the House of Commons.

The protest organizers described the theme of this year's rally as what they called gendercide, or sex-selective abortion, an issue Canada's political parties have gone out of their way not to deal with. At times the crowd chanted "save girls."

Fighting for women's rights and against sex-selective abortion: these are the new arguments of the anti-abortion movement.

'Need to change the hearts of the people'

Andre Schutten speaks for the Association for Reformed Political Action, a group that wants legal limits on abortion.

"In order to change the law, we need to change the hearts of the people first," Schutten said in an interview with CBC News.

"We will continue to push for restrictions until the law values and protects every human being in the human family equally," he said.

In the past, Schutten added, abortion was painted as a choice between right and wrong, moral and immoral.

Parliamentarians at the rally: MPs (all are Conservative caucus members): Harold Albrecht Stella Ambler Rob Anders David Anderson Leon Benoit Kelly Block Rod Bruinooge Dean Del Mastro Royal Galipeau Ed Komarnicki Guy Lauzon Wladyslaw Lizon James Lunney LaVar Payne Kyle Seeback Bev Shipley Kevin Sorenson Lawrence Toet Brad Trost Dave Van Kesteren Maurice Vellacott Mark Warawa Jeff Watson John Williamson Stephen Woodworth Bob Zimmer Senators (both Conservative): Norman Doyle Tobias Enverga

Now the focus is on human rights and compassion for a woman in a crisis pregnancy.

Paul Saurette, a political studies professor at the University of Ottawa, is writing a book about how discussion about abortion is changing.

He says people opposed to abortion are adopting new language to make their case.

"It's much more centred on the argument that abortion harms women and that's why Canadians should support the anti-abortion position," Saurette said.

'Paralleling' feminist movement

But there isn't a great deal of evidence about the effect of abortion on women, Saurette added.

"The abortion harms women arguments, I think when you look at the medical evidence behind it, it's extremely questionable."

Kelly Gordon, a PhD candidate at the University of Ottawa and co-author with Saurette, said activists campaigning for limits on abortion are aligning themselves with more progressive human rights movements, citing leaders like Martin Luther King Jr.

"They're really paralleling themselves with the feminist movement... they're really using that protect girls language," she said.

That language was used throughout Thursday's rally.

"Baby girls in our beloved country of Canada are being killed just for being girls. This is the most unjust form of discrimination facing our country today," said Alissa Golob, youth co-ordinator for Campaign Life Coalition.

Former Liberal MP Pat O'Brien was among the speakers at the rally, which got underway shortly after noon.

"We stand here on Parliament Hill, and we say to the leaders behind us, 'Be not afraid, be not afraid of the debate. It's time to have the debate,'" he told the crowd.

Organizers of the annual rally and march through Ottawa's downtown streets said yesterday at a news conference that Prime Minister Stephen Harper has been trying to shut down any form of debate related to abortion. Harper has consistently said he will not reopen the abortion debate while in office.

During the rally on the steps of Parliament Hill, the crowd was encouraged to sent tweets to Harper saying they want abortion abolished in Canada.

MP asks for support in next election

"The men behind me have taken strong stands, and they have made enemies doing so," Conservative MP Rob Anders said as he stood in front of a group of his caucus colleagues. He asked the crowd to get their friends to support their cause when candidate nominations come up for the next election in 2015. "They will need the help of those people in order to carry on their work and push it further down the field. Please consider that."

One woman in the crowd who helped organize the event said support for the Conservatives could suffer next time voters go to the polls because of how they have handled the abortion issue.

"Many people are disappointed, we expected more of them," said Wanda Hartlin. "I've had many people tell me that they're reconsidering where they're going to put their vote next time."

"The Conservatives have not followed through on family issues the way we hoped they would have," she said.

Pro-choice protesters were at the anti-abortion March for Life rally on Parliament Hill on Thursday. (Sean Kilpatrick/Canadian Press)

Conservative MP Del Mastro told the crowd that the winning the fight for life involves winning hearts and minds. "The only way we'll win hearts and minds in this country is with love. Love is our weapon. Let's fight for life, let's show love and let's win this."

Conservative MP Mark Warawa, who has been front and centre of recent debates on Parliament Hill, also spoke at the rally.

"Together we will keep up the fight and we will win," he said. "We all work hard together."

In question period, Warawa used his member's statement to recognize those who are fighting to end sex-selective abortion. "Gendercide is the ultimate form of discrimination against women and girls," he said.

Warawa tried to spark a debate on sex-selective abortion in March, but found out shortly before he was to make a statement in the House that he'd been removed from a list of MPs selected to speak that day. An all-party committee of MPs declared his motion ineligible and he instead submitted a private member's bill that will limit where sex offenders can live.

Pro-choice protesters were also on Parliament Hill and NDP MP Niki Ashton joined them to show her support.