Saturday's rally in Madrid was organized by women's groups and organizations that support reproductive rights. Shouting slogans and carrying banners that read "It is my right, it is my life," "Allow mothers to decide" and "Mothers and fathers in freedom," demonstrators crowded around a train station to greet more protesters arriving from northern Spain, marching then to the national parliament.
In December, the conservative People's Party (PP) government led by Prime Minister Mariano Rajoy made good on its 2011 election promise to re-introduce laws severely curtailing the ability of women to abort a pregnancy.
A draft bill, which still needs approval by parliament, where the People's Party has an absolute majority, is a rollback of a 2010 law from the previous Socialist government. That law legalized abortion on demand in the first 14 weeks of pregnancy, bringing Spain into line with most of the rest of Europe.
The new law would allow abortion only in cases of rape or a threat to the health of the mother, and oblige girls under 18 to get their parents' consent to have abortions.
It would also toughen conditions for aborting in cases of malformation of the fetus. The current law authorizes this freely up to 22 weeks.
Pro-choice campaigners said on Saturday the new legislation would return Spain to conditions similar to that of a more restrictive 1985 law.
"This is a step backward. We're going back 30 years," said 58-year-old Pilar Abad.
"We really hope that they'll change this bill during the parliamentary debate, that's why we're here," she added.
The bill, introduced under pressure from the Catholic Church, is seen as an attempt to appease the disgruntled right wing of the People's Party. It has not yet been submitted to parliament for debate.
Spain's top Roman Catholic Cardinal Antonio Maria Rouco Varela said last April that the 2010 law had "led to a rise in the number of abortions to terrifying levels." Campaginers however dispute the effect of the legal changes on abortion numbers.
The national health ministry said there were about 118,000 abortions in Spain in 2011, up around 5,000 from the previous year.
Critics have said Rajoy has failed to build party consensus for the bill. Rajoy himself recently signaled he was open to modifying the proposal.
"A political party has to take into account what voters think. Voters have spoken through the opinion polls," said Celia Villalobos, a People's Party MP who supports abortion on demand.
Polls in Spain show around 80 percent of people, including practicing Catholics, support abortion on demand.
jr/kms (Reuters, AP, AFP)