The world's largest review of the impact of abortion on women's mental health has concluded that terminating a pregnancy does not increase the risk of mental problems in women who choose it.

Instead, the review found they already have a higher rate of mental problems by virtue of having an unwanted pregnancy. The outcome of the pregnancy did not affect their mental health.

The findings will reassure the 200,000 women a year who have an abortion in the UK. But they were attacked by anti-abortion organisations. Published by the Academy of Medical Royal Colleges, the study was based on 44 research papers selected from 180, and included hundreds of thousands of women. Previous reviews have produced conflicting results.

Dr Tim Kendall, director of the National Collaborating Centre for Mental Health, which carried out the study, said: "We believe we have used the best-quality evidence available and that this is the most comprehensive and detailed review worldwide."