Nicaraguan President Enrique Bolanos has signed into law a ban on all abortions, even in cases when a woman's life is judged to be at risk.
Nicaragua's abortion law provoked emotional debate
Previous legislation from a century ago allowed an abortion if three doctors certified that the woman was in danger.
Abortion was a central issue for November's presidential election in mainly Roman Catholic Nicaragua.
President-elect Daniel Ortega once favoured abortion rights but changed stance after re-embracing Catholicism.
Mr Bolanos signed the law in the presence of Roman Catholic bishops and Protestant evangelist leaders.
The new legislation would help protect the right to life enshrined in the Nicaraguan constitution, a statement on the presidency's website said.
The law abolished abortion rights "which allowed the daily execution of innocent children in their mother's womb, in open violation of the Constitution which protected the unborn child", the statement said.
Nicaragua already had strong anti-abortion laws, with women and doctors who take part in abortions facing prison sentences of up to six years.
But in October the national assembly unanimously approved the new ban.
The timing of the vote was opposed by Nicaragua's medical association and representatives from the United Nations and European Union, who warned that the debate had become politicised ahead of the election.
Doctors and women's rights campaigners also argued that the change in the law would increase maternal deaths and infant mortality.
The former Sandinista leader Daniel Ortega was a defender of Nicaragua's limited abortion rights and a critic of the Catholic church when he led a left-wing Nicaraguan government in the 1980s.
He has since been reconciled with the church and has become a strident opponent of abortion.
Public opinion in Nicaragua, which is estimated to be 85% Roman Catholic, appeared to be behind the bill.
Similarly strict laws are in place in Chile and El Salvador.
In many other Latin American countries, abortion is permitted if the woman's life is in danger.
In May, abortion restrictions were partially eased in Colombia to permit terminations in cases of rape, incest or if the life of the mother or foetus is in danger.