Monday December 1 2008
The study does not prove that abortions cause mental health issues
“Women who have an abortion are 30% more likely to develop a mental illness”, reported The Sunday Telegraph. A recent study has found that women who have an abortion are also three times more likely to develop drug or alcohol addictions compared with other women.
The study in question looked at links between abortion and mental health by following over 500 women for several years. Researchers found a modest association between women who have had an abortion and common mental health problems, compared with women who had never been pregnant.
However, this study does not prove that abortions cause mental health issues or vice versa. A number of factors not measured in this study may be partially responsible for the association. Also, women who had a termination were only compared with women who had never been pregnant, and not women who had given birth.
Where did the story come from?
Doctors David Fergusson, John Horwood and Joseph Boden carried out this research. It was funded by grants from the Health Research Council of New Zealand, the National Child Health Research Foundation, the Canterbury Medical Research Foundation and the New Zealand Lottery Grants Board. It was published in the peer-reviewed, British Journal of Psychiatry.
What kind of scientific study was this?
This was a prospective cohort study looking at pregnancy and mental health outcomes in a subset of women enrolled in the Christchurch Health and Development Study (CHDS).
In the CHDS, 1265 children born in Christchurch, New Zealand were followed up at various ages until they were 30 years old. Information was available on pregnancy history and mental health outcomes for 534 women in the study.
The CHDS assessed women at ages 15, 16, 18, 21, 25 and 30 years, asking about the timing and outcomes of any pregnancies since their previous assessment. The CHDS also asked about emotional reaction to these pregnancies and the extent of any related `distress.
At age 30, the women were asked to record their full pregnancy history to date, including timing and outcomes as well as their emotional response. Emotional response was recorded in a five-point system, ranging from very happy to very unhappy/distressed. The researchers used information from this final assessment to ensure previous assessments were accurate, and used a combination of retrospective and prospective data in their analysis.
The outcomes of pregnancies were categorised as: elective termination (i.e. a termination they had chosen), loss of pregnancy (miscarriage, stillbirth, termination of ectopic pregnancy), live birth with an adverse reaction to pregnancy (either unwanted or distressed because of it), and live birth with no adverse reaction.
During the follow-ups at age 16 and above questionnaires were used to assess participants’ mental health and to diagnose potential major depression, anxiety disorders, alcohol dependence and illicit drug dependence. Researchers also measured a range of other factors including socioeconomic status, living standards, exposure to child abuse, personality and sexual behaviour.
The researchers analysed the link between the women’s mental health during pregnancy. They then analysed pregnancy in the five years prior to each mental health assessment. In this way they attempted to establish whether the pregnancy preceded changes in mental health.
What were the results of the study?
From several conclusions made by the researchers the most robust is that having a termination increased the rates of mental disorders. They say that women who had a termination had on average 1.32 (1.05–1.67) times the number of mental health problems of women who did not become pregnant.
This is based on a five-year lagged model that took into account other factors that may be linked with mental health or pregnancy outcome such as education, family stability and financial status.
What interpretations did the researchers draw from these results?
The researchers conclude that the evidence is consistent with the view that termination may be associated with a small increase in the risk of mental disorders. Other pregnancy outcomes such as live birth were not related to an increased risk of mental health problems.
What does the NHS Knowledge Service make of this study?
Importantly, the researchers acknowledge that the overall effects of termination on mental health were small and that termination was responsible for only 1.5% to 5.5% of the overall rates of mental health problems seen in this group of women. Given this more cautious interpretation of the risks by the researchers, the newspapers may have over interpreted the findings of this study.
This study also relies on data that has been collected as part of a large cohort study. There are some problems with this analysis that should be kept in mind when interpreting the results:
- The researchers chose to compare women who had a termination with those who never got pregnant. Perhaps a comparison with women who decided not to have a termination, especially those who had negative feelings about their pregnancy, might have been more informative.
- This study does not clearly show whether there is any effect on mental health – good or bad – among women who had a termination compared with those who were ‘distressed’ but still went ahead with their pregnancy.
- Women who choose terminations may do so for a variety of different reasons. The emotions and experiences associated with termination vary too, and these may have an impact on later mental health. These reasons and experiences surrounding elective termination were not taken into account in this study.
- The study did not adjust for the multiple comparisons it made. This means that significant results are more likely to have occurred by chance.
- Interpretation of results from cohort studies is usually difficult because other unmeasured factors may be responsible for the associations they measure. While the researchers attempted to adjust for this, it can never be done perfectly, so unmeasured factors may be responsible for the results in this study.
In an accompanying editorial for this study, Patricia Casey (a psychiatrist not involved in this research) and her colleagues acknowledge the need for evidence-based interventions to support women who choose to have a termination, and for training of healthcare professionals about their needs.
It is well recognised that pregnancy is associated with mental health problems, whether or not a woman chooses a termination. The important issue is to identify women who are at risk and provide them with the right support, whatever decisions they make.