Having an abortion does not increase a woman's risk of developing breast cancer, researchers have found.
The study looked at breast cancer risk
A study of just under 4,000 women by doctors at Sweden's Karolinska Institute found no link between terminations and the disease.
Some studies have suggested abortions could increase the risk of cancer, but many experts say the evidence is weak.
Last week three MPs sent out their own survey to UK doctors in a bid to examine the potential link.
Researchers identified 1,759 women who had given birth between 1973 and 1991 and then gone on to develop breast cancer by comparing data from the Swedish Medical Birth Register and the Swedish Cancer Register.
They then looked at the same number of cases from the birth register who had not gone on to develop cancer.
All had been asked if they had previously had any abortions while receiving maternity care.
Researchers found 383 of those who went on to develop breast cancer and 473 of those who did not had had at least one abortion, suggesting terminating a pregnancy was not linked with an increased risk of breast cancer.
In fact, women who had had at least one abortion had a reduced risk of breast cancer compared to those who had none.
Dr Gunnar Larfors, who led the research, said: "We have looked at some 4,000 journals from maternity centres in which women have responded to standardised questions about abortions, among other things, and have not found any correlation between abortions and increased risk of breast cancer.
"In fact, aborted pregnancies had some preventive effect in our study."
It has been known for some time that pregnancy had a preventive effect against breast cancer, although it is not yet clear why this is the case.
Mr Larfors said abortion was still a taboo subject, so if women on the street were asked, they might be unlikely to admit that had had one.
But he said a woman who had suffered from breast cancer was asked about previous abortions would probably answer truthfully.
He added: "This can skew the results to make it seem as if breast cancer is tied to abortion.
"In our study all women had answered the same question before developing breast cancer."
Following the concerns raised last week, Professor Joel Brind, from City University of New York, who claims his findings suggest a link between abortion and breast cancer after being invited by pro-life campaigners Life, is to speak to MPs on Wednesday.
Professor Jack Scarisbrick, chairman of Life, told BBC News Online full term pregnancies had been shown to have a protective effect against breast cancer, but abortion did not. because the excess oestrogen produced in early pregnancy was not processed by the body as it would be if the pregnancy continued.
Research has shown a link between levels of the female sex hormone, oestrogen, and the risk of developing breast cancer.
He added: "If a woman has an abortion before they have a baby and they have a family history of breast cancer, they are virtually signing their own death warrant."
And he said the Swedish findings would not be relevant to other countries.
"In Sweden, most abortions are done after women have had children as a way of limiting family size.
"In countries like the US, UK and France, they are done to delay starting a family."
But breast cancer campaigners urged women not to be unduly worried.
Christine Fogg, joint chief executive of Breast Cancer Care, said: "Current research has consistently failed to show any link between induced or spontaneous abortions and breast cancer risk."
She said "scare stories" which claimed to show a link increased the anxiety of many women.
"We want to reassure women that there is no proven link between abortion and the risk of breast cancer and that age remains the strongest risk factor for breast cancer."