With 31 votes in favour, 38 votes against and two abstentions the voluntary termination of pregnancy bill is rejected.
The bill, which fueled contentious debate, would have expanded abortion rights to allow women to end a pregnancy in the first 14 weeks.
Abortion has always been illegal in Argentina: Currently, if a woman is found to have undergone the procedure (in instances other than rape or if the mother's life is in danger), she can be jailed for up to four years.
Lawmakers debated the bill for more than 16 hours, during which pro-choice Sen.
The issue has bitterly divided Argentines, pitting conservative doctors and the Roman Catholic Church against feminist groups and other physicians. In 2010, HRW claimed that Argentina's abortion ban violated global treaties, even though none of the cited treaties mention abortions.
Soros also funds the pro-abortion Human Rights Watch (HRW), which has worked to pressure pro-life countries to legalize abortion.
"Fortunately, women are gaining spaces and we've been learning from those spaces that they're demanding", said Gustavo Bayley, a tattoo artist wearing the abortion movement's green handkerchief on his arm.
Meanwhile, at the city's Metropolitan Cathedral, a "mass for life" was held in support of keeping laws unchanged.
Supporters of the bill held protests for months under the banner of Ni Una Menos, a coalition of women's rights groups.
The proposal can not be brought up for debate until next year, but Argentina's Senate is set to discuss abortion again late this month when it considers reforms to the country's penal code, reported La Nación.
Backers of the measure said legalizing abortion would save the life of many women who now turn to unsafe illegal abortions. Moreover, efforts to present abortion as a health emergency, calling clandestine abortions the primary cause of maternal death in the country, statistics show that this claim is simply false.
At the same time, Cardinal Poli called on Catholics to find space in their communities to allow pregnant women in difficulty "to share their fears and to feel the embrace and tenderness of women who had the joy of giving birth to a child, despite all difficulties". Women who asked for an abortion would have had to wait no more than five days to get one. There are three exceptions: if a woman is raped, pregnancy puts her life in danger, or a fetus is brain-dead. Chile had been the last country in South America to ban abortion in all cases, though several nations in Central America still have absolute prohibitions. In 2010, it became the first country in Latin America to legalize same-sex marriage.
"It is not a question of beliefs, but of a problem that exists", Fernandez said.