MEXICO CITY - Gay couples lined up in the Mexican capital on Thursday to get a date to tie the knot as the city becomes the first in mostly Catholic and typically macho Latin America to allow same-sex marriage.

The law, now in effect after being approved by the city's mainly left-wing legislature in December, goes beyond current law allowing same-sex civil unions to give gay couples the same marriage rights as straight couples, including adoption.

Some other Latin American countries including Argentina and Uruguay allow same-sex unions but Mexico City is the first place to include gay couples within existing marriage laws.

"We have fought so hard to get this, and now that it is a reality, it seems like a dream," said Ema Villanueva, 34, who is raising a 5-year-old daughter with her partner Janice Alva.

They were among the first couples arriving at civil registries with birth certificates and other documents they
need to submit to get married as soon as next week.

The Mexican capital has become a bastion of liberal policies in the largely conservative nation, which has the
world's second-biggest Catholic population after Brazil.

Since winning control of the Mexico City government in the late 1990s, Mexico's main left-wing party has brought in pensions for the elderly and better schools for the poor while also moving to make divorce easier, decriminalize abortion and allow terminally ill patients to refuse treatment.

The Catholic Church has slammed the same-sex marriage law, with the country's top churchman, Cardinal Norberto Rivera, saying it was "perverse" and an attack on the family.

Conservative President Felipe Calderon has also challenged the law, filing a suit with the Supreme Court to overturn it on the grounds marriage should be between a man and a woman. The court has not yet decided whether to take up the case.

"This is not normal," scoffed housewife Patricia Fournier, watching same-sex couples emerge from a civil registry.

"How do you explain to kids that their parents are two men or two women?"

Proponents of gay marriage cite dozens of studies that say children raised by same-sex couples are at no disadvantage to peers from traditional families. Some still fear a backlash, however, especially outside the capital.

"I don't think people are prepared for an advance this big. There is a lot of prejudice," said Rodrigo Cervantes, standing next to his Italian partner, Mirko Marzadro. The two live in Venice but have traveled to Mexico to get married.

"I thought I would get married in any other country except Mexico," Cervantes said. "But here we are."