Key Points:

Women who have an abortion are more likely to suffer subsequent poor mental health, according to a new survey.

The University of Otago study found women who had an abortion faced a 30 per cent increase in the risk of developing common mental health problems such as depression and anxiety.

Professor David Fergusson, John Horwood and Joseph Boden studied the pregnancy and mental health history of over 500 women, who took part in the long-running study from birth to the age of 30.

The women were interviewed six times between the ages of 15 and 30, each time being asked whether they had been pregnant and, if so, what the outcome of that pregnancy had been.

They were also given a mental health assessment during each interview, to see if they met the diagnostic criteria for major depression, anxiety disorders, alcohol dependence and illicit drug dependence.

Overall, 284 women reported a total of 686 pregnancies before the age of 30. These pregnancies included: 153 abortions (occurring to 117 women), 138 pregnancy losses, 66 live births that resulted from an unwanted pregnancy, and 329 live births resulting from a wanted pregnancy.

The study found the overall population effects of abortion on mental health were small, with researchers estimating that exposure to abortion accounted for between 1.5 and 5.5 per cent of the overall rate of mental disorders in the general population.

However, the findings have implications for the legal status of abortion in New Zealand where over 90 per cent of terminations were authorised on the grounds that proceeding with the pregnancy will pose a serious threat to the woman's mental health.

The study supports international research on the subject which also revealed a link between abortion and mental health.