DUBLIN, Ireland — They board flights or ferries to England every day: lone females, usually in their 20s, pregnant and carrying little more than an overnight bag.

They are women forced by a ban on abortion in Ireland to travel overseas to terminate their pregnancies.

Now Ireland will have to amend its long-standing laws on abortion, following a ruling today by the European Court of Human Rights.

The exodus is likely to continue at near the current rate of about 12 a day, however, as the ruling does not challenge the ban on abortion where a woman's life is not considered at risk.

Sitting in Strasbourg, France, the court declared that Ireland had failed properly to implement the constitutional right to abortion in cases where a woman’s life is in danger.

It ruled in a test case that a woman with a rare form of cancer, known only as "C," should not have been denied abortion, as her unintentional pregnancy could have caused a recurrence of the disease.

The 17-judge tribunal concluded that the human rights of two other women, "A" and "B," were not breached.

One was a recovering alcoholic with four children in foster care who felt another pregnancy would harm her chances of getting them back.

The other did not want to become a single parent and had been advised that her risk of ectopic pregnancy was not sufficient to justify an abortion under the Irish constitution.

Abortions in Ireland are allowed only if there is “a real and substantial risk to the life, as distinct from the health, of the mother,” the court noted.

The risk to the life of "C," a Lithuanian woman living in Ireland, “clearly concerned fundamental values and essential aspects of her right to respect for her private life,” it said.

"C" was unable to find a doctor in Ireland willing to perform an abortion on the grounds that her life would be at risk if she went the full term. If an abortion had been successfully challenged in court, both the woman and the doctor ran a risk of a criminal conviction and imprisonment.

As a signatory to the European Convention on Human Rights, Ireland is obliged to comply with its rulings.

The prohibition on abortion in Ireland was endorsed by a referendum in 1983 which declared that an unborn child is an Irish citizen with full rights. Another referendum in 1992 cleared the way for legislation that allows women to leave the country to have an abortion. This followed an outcry in the case of a young teenager prevented by police from leaving the country for an abortion after being made pregnant by her babysitter.

The latest government estimates show that in 2008 up to 683 women developed complications during pregnancy that warranted a legal abortion in Ireland.

However, some 4,400 women with addresses in Ireland sought abortions in British clinics in 2009, according to the United Kingdom Department of Health. Most were aged between 20 and 29 and were typically between three- and nine-weeks pregnant.

Abortion rights campaigners in Ireland welcomed the ruling in the case of "C," but expressed disappointment that the court had not upheld the other two challenges.

“We are deeply saddened that the court chose not to recognize the hardships faced by the other two claimants,” said Mara Clarke, director of Abortion Support Network, a voluntary organization in Dublin that helps women travel to Britain for abortions.

Health Minister Mary Harney said that new legislation would have to be considered following the ruling. The ruling is also likely to renew pressure in Ireland for another referendum to change the constitution to ease the ban on abortion.

This would be vigorously opposed by pro-life groups though their influence has been weakened with the decline in the authority of the Catholic Church in Ireland, following sex abuse scandals involving priests and a trend toward secularization.

The European Court of Human Rights rules on human rights issues among the 47 member states of the Council of Europe. It is not part of the European Union.