A number of Conservative motions, ranging from lowering the legal limit to between 12 and 22 weeks, were rejected. In the last of a series of votes, members of parliament (MPs) defeated a reduction to 22 weeks by a vote of 304-232.

The parliamentary debate on abortion was part of a current overhaul of Britain's Human Fertilization and Embryology Bill, which has already seen radical changes in laws governing embryo and stem-cell research.

A lowering of the gestation limit would have marked Britain's first major change in abortion law since 1990, when the limit was cut from 28 to 24 weeks.

The 24-week limit is double that of France and Germany, six weeks later than Sweden and Norway and the same as in the Netherlands.

Pro-life campaigners argued that medical advances have raised survival rates for babies born between 22 and 25 weeks gestation from 32 percent in 1981 to 71 percent in 2000.

But other research has shown that there is no improvement in "viability rates" for babies born before 24 weeks.

Number of abortions increasing in Britain

Pro-choice campaigners point out that only 1.5 percent of the annual 200,000 abortions in Britain are carried out after 20 weeks of pregnancy.

The British Medical Association (BMA), the country's biggest association of doctors, came out in favor of keeping the 24-week limit, as has Labour Prime Minister Gordon Brown.

"The medical evidence has not changed, and that is why I will support the 24 weeks," Brown said ahead of the vote.

Conservative MP Nadine Dorries, who initiated a motion to cut the time limit to 20 weeks, said action was needed to reduce the fast-rising number of abortions in Britain.