Abortion, say medical experts, is a pretty safe procedure when carried out in the early weeks of pregnancy. This is the official view on the Department of Health's NHS Choices website: "No clinical procedure is entirely free from risk, but abortion poses few risks to a woman's physical health, particularly when carried out during the first 12 weeks of pregnancy. An abortion does not usually affect a woman's chances of becoming pregnant and having normal pregnancies in future."

That does not stop the controversy – fuelled, say pro-choice campaigners, by misinformation or deliberately partial interpretations of research. Among the myths circulated are that abortion increases a woman's risk of breast cancer or can make her infertile

Only this month, a study emerged from the European Society for Human Fertilisation and Embryology conference in Stockholm involving records for more than a million pregnancies in Scotland over 26 years. The top line was that women who have had an abortion are subsequently more likely to give birth prematurely. The reasons for this finding may be nothing to do with abortion.

First – and particularly in the past – many women would not have disclosed an abortion, which distorts the numbers. There was no difference in the rate of premature births between women who had an abortion and those who had a miscarriage. Second, this study found, as have others, that women who have had an abortion are more likely to be smokers, older and from poorer socio-economic backgrounds, all of which make them more likely candidates for premature delivery.

Not all studies take that into account. The Royal College of Obstetricians and Gynaecologists, in its guidance on reproductive outcomes after termination of pregnancy, states: "The confounding effects of socio-economic factors, which are important, are considered in very few studies examining the effects of induced abortion."

There is a lack of consensus on a possible risk of preterm birth, it says. Some studies found an association, others not. "From the recent studies reviewed, no clear relationship between previous induced abortion and preterm birth was demonstrable," the guidance says. Also, there "are no proven associations between induced abortion and subsequent ectopic pregnancy, placenta praevia or infertility".

Patricia Lohr, medical director of the British Pregnancy Advisory Service, dismissed claims that abortion increases the risk of cancer. "Multiple large studies have now demonstrated that there is no association," she said.

Another myth, she said, is that it causes "post-abortion syndrome" – a psychological disorder triggered by regret. "There is no such diagnosis. We know from large studies that there is no association between having one abortion and an adverse psychological outcome."

Indeed, research showed that most women – once past the agonising stage of decision-making and having gone through the procedure – felt relief.