Pope Benedict XVI had endorsed a call by Italy's politically influential Catholic Church for Italians to boycott the referendum vote held Sunday and Monday.
The four ballot measures drew 25.9 percent of eligible voters, roughly half of the required turnout of 50 percent plus one for the referendums to be binding on Parliament.
It was a humiliating defeat for those who drew the Church's ire in seeking to undo some of Europe's strictest regulations on assisted fertility.
Had they succeeded in gutting the 2004 law, the referendums would have ended a limit to the number of embryos that can be created at one time and lifted bans on freezing them for future implantation or on screening them for defects. Success at the polls would also have scrapped a provision of that puts embryos on par with the born in terms of legal rights.
The Holy See's press office said it planned no comment.
But the Vatican's missionary news agency Fides touted the referendums' failure as proof of its pulling power in predominantly Roman Catholic Italy, an officially secular state that hosts the Holy See on its territory.
"Catholics are united on fundamental values, starting from the supreme value of human life," Fides said.
Cardinal Camillo Ruini, the Italian bishops conference leader, who championed the boycott appeal, dismissed talk that the Catholic church was the "victor."
"What really won was the moral conscience of our people and the future of man himself," Ruini said in an interview on private Canale 5's evening news.
Some Italians sounded taken aback by the referendums' poor drawing power.
"I didn't expect such a low turnout," said Domenico Costantino, 29, who is a fund-raiser in Rome for the British aid group Save the Children. He said the intervention of the church and of political parties had influenced people's choices.
"I am not disappointed that the referendums failed," said Carmen Maulicino, a shop assistant in Rome. "The cycle of life is a natural thing and we should not interfere by manipulation."
A recent Associated Press-Ipsos poll found that nearly two-thirds of Italians think religious leaders should not try to influence government decisions. And in random interviews, many denounced the church's appeal as invasive.
"We lost, and we lost heavily," said Daniele Capezzone, a leader of the Radical Party, which battled to overturn the law. Commenting on the church's aggressive campaign, Capezzone worried that churchmen would now wage war on laws permitting divorce and abortion.