Pro-choice campaigners mark 40 years of legal abortion in Britain next week, but say their hard-won right is under pressure from pro-life activists trying to lower the 24-week limit for the termination of pregnancy.
Passionate debate over the ethics of aborting healthy babies preceded the Abortion Act that came into force in April 1968, and the issue is still hotly contested by the two sides.
"I used to - and still occasionally do - get lunatic letters comparing me to Herod and Hitler," David Steel, the parliamentarian who introduced the Act, told Reuters.
Forty years after Steel saw the Act become law, parliament is again besieged by activists - one group determined to stop what it sees as the barbaric murder of innocents, the other fiercely defending what it says is women's right to manage their own lives.
"The Abortion Act and its enactment was an historic advance for women," said Louise Hutchins, campaign director for the Abortion Rights group. "It ended the days of backstreet abortion with thousands of women being killed and many thousands more being injured and maimed for the rest of their lives.
"Not only that, it also allowed an incredible advancement in women's economic, social and educational position in society by giving them basic control over their lives."
Russia was the first country to legalise abortion in 1920, according to the World Health Organisation - although the law was repealed in 1936 and abortion remained illegal until 1955. Iceland was the first west European country to legalise abortion, in 1935.
TIME LIMIT
Many European countries allow abortion on demand up to 12 or 13 weeks into pregnancy, after which it is limited to cases where the baby or mother is at risk. It is legal up to 22-24 weeks of pregnancy in Spain, Switzerland and the Netherlands.
Britain's law originally allowed abortions up to 28 weeks after conception as long as two doctors agreed, but the upper limit was reduced to 24 weeks in 1990.
Pro-life campaigners, arguing that the upper limit should be reassessed, plan to table a series of amendments to a human fertilisation bill going through parliament next month, seeking a reduction to 20 weeks, 18 weeks, or even lower.
One of the strongest influences on the debate has been the release of groundbreaking three-dimensional moving images produced by Professor Stuart Campbell, an obstetrics specialist and a pioneer of ultrasound foetal diagnosis.
His video clips and photographs clearly show foetuses as young as 16 weeks sucking their thumbs, yawning and demonstrating behaviour which suggests they are far more developed at this stage than was previously thought.
