No high-quality study done to date can document that having an abortion causes psychological distress, or a "post-abortion syndrome," and efforts to show it does occur appear to be politically motivated, US researchers said yesterday.

A team at Johns Hopkins University in Baltimore reviewed 21 studies involving more than 150,000 women and found the high-quality studies showed no significant differences in long-term mental health between women who choose to abort a pregnancy and others.

"The best research does not support the existence of a 'post-abortion syndrome' similar to post-traumatic stress disorder," said Dr Robert Blum, who led the study published in the journal Contraception.