Campaigners on both sides of the debate are lobbying MPs
Britain needs to send a "less casual message" about abortion, an MP has said as she launches her bid to reduce the upper limit from 24 to 20 weeks.
Nadine Dorries says Britain risks becoming Europe's "abortion capital".
Her amendment to the Human Fertilisation and Embryology Bill would lower the upper limit.
Health Secretary Alan Johnson said he believed the original limit "stood the test of time" but MPs would be given a free vote on the issue.
Both sides of the debate are lobbying MPs ahead of a possible vote on the issue later this month.
Ms Dorries, a former nurse who has made several previous attempts to reduce the upper limit, launched her campaign saying "Britain has 200,000 abortions a year, or 600 a day. That is just too many, we must slow down on abortion."
The Tory MP said she respected "a woman's right to choose" but added: "It is now time to adopt a more moderate, commonsense approach to abortion."
She argues that increasingly babies born at 24 weeks are surviving.
The prospect of a vote on reducing the upper limit has prompted campaigners on both sides of the debate to lobby MPs.
At Commons question time earlier, junior health minister Ann Keen said only 12% of babies born less than 24 weeks into pregnancy, survived past their first birthday.
She said there was "no evidence of a significant improvement" in survival rates in the last 18 years in the UK.
Lib Dem MP Evan Harris, a former hospital doctor, added: "The best research, which looks at every birth rather than a selected sample ... failed to show any reduction since 1995 in the threshold of viability below 24 weeks."
And Health Secretary Alan Johnson said "as an individual", he did not want to see the law changed and believed the original legislation had "stood the test of time".
But Conservative MP Philip Hollobone said it was "truly appalling" that in England in 2006, there were 59,687 abortions by women who had already had at least one abortion.
Medical organisations, including the British Medical Association and Royal College of Obstetricians and Gynaecologists, have said they are in favour of the 24-week limit.
MPs who agree with the current limit are expected to put forward a proposal to relax abortion laws by scrapping the need for two doctors to agree to a termination and allowing nurses to carry them out in the early stages.
MPs will be given a free vote on any abortion-related amendments when the bill is debated.