A power struggle has erupted in Guatemala over a family planning law.
Guatemala has one of the highest birth rates in the region
The law was vetoed by President Oscar Berger, but congress decided to enact it unilaterally on Tuesday.
The new legislation requires the government to promote the use of contraceptives and provide sex education classes.
Guatemala has one of the highest birth rates in Central America, and infant mortality and malnutrition are among the highest in the region.
After revoking the presidential veto, congress ordered the publication of the bill in the official state gazette.
The government claimed the process was "irregular" because only 80 legislators voted against the veto instead of the 106 it said were needed.
President Berger and representatives of the Roman Catholic Church have vowed to present legal challenges.
"We will appeal the decision before the Constitutional Court", Mr Berger told reporters.
The Archbishop of Guatemala City, Rodolfo Quezada Toruno, said the family planning bill would open the door to abortion by promoting what he called a "culture of death".
He compared the effect of contraceptives with that of "bullets".
However, representatives of women's groups who had gathered outside the congress building welcomed the rejection of the presidential veto.
In Guatemala, only 40% of women use any form of birth control, including natural methods.
Half of the country's women have a child before the age of 19, and 20% have two or more children by their 18th birthday.