The Conservative Status of Women Minister who voted in favour of Wednesday night's failed motion to study the legal rights of the fetus was hit with a torrent of criticism overnight from pro-choice Canadians.

MPs voted overwhelmingly against the motion, but 10 Conservative ministers – representing more than a quarter of Prime Minister Stephen Harper's cabinet – supported it. Dozens more backbench Conservative MPs and four Liberals also voted in its favour.

Minister of Intergovernmental Affairs Peter Penashue, Citizenship and Immigration Minister Jason Kenney, International Co-operation Minister Julian Fantino, National Revenue Minister Gail Shea, International Trade Minister Ed Fast, Agriculture Minister Gerry Ritz, Minister of State for Seniors Alice Wong and Minister of State of Foreign Affairs Diane Ablonczy all voted for the motion.

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Currently, a child is considered a human being under the law only once it has emerged completely from its mother's body. The private member's motion proposed by Conservative MP Stephen Woodworth sought to study whether a fetus should have legal rights before birth.

Status of Women Minister Rona Ambrose surprised many with her vote in favour of the motion because of the file she is responsible for. In the hours after the vote, photos of Ms. Ambrose appeared on social media sites with the text, "Canada's Minister for the Status of Women just voted to criminalize abortion." Some wrote open letters to the minister or took to Twitter to call for her resignation.

"Not only did your turn your back on the women you are supposed to represent, you turned your back on the history of struggle that women faced that led to the creation of the position you currently hold in cabinet," Facebook user T.J. Jardine wrote in an open letter to Ms. Ambrose.

Bloc Québécois MP Maria Mourani said she was disappointed Ms. Ambrose voted in favour of the motion and suggested she should resign as Minister for the Status of Women.

"She has to think about [stepping down]," Ms. Mourani said on Wednesday night. "Because if she doesn't fight for women's rights, I don't know what she does in this place."

Responding to a question on Twitter Wednesday night, Ms. Ambrose connected the decision to her concerns about sex-selective abortion.

"I have repeatedly raised concerns about discrimination of girls by sex-selection abortion," she wrote when asked to explain her vote, adding, "No law needed, but we need awareness!"

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In April of this year, Ms. Ambrose scolded a Vancouver-area publication for running an advertisement for a gender selection facility in Washington State. The clinic is capable of determining the sex of an embryo before using it as part of in-vitro fertilization, allowing parents to have greater control over their child's sex.

This is not the first time Ms. Ambrose has voted in favour of a bill related to the rights of the fetus. In 2008, she was among a majority of MPs who voted to send a bill to committee that would make it a criminal offence to injure or kill an unborn child while committing an offence. That bill specifically excluded abortions performed with a woman's consent. It was referred to committee but did not go further.

Click here for a full list of how the MPs voted