Given the methodological limitations of recently published qualitative
reviews of abortion and mental health, a quantitative synthesis was
deemed necessary to represent more accurately the published literature
and to provide clarity to clinicians.
To measure the association between abortion and indicators of adverse
mental health, with subgroup effects calculated based on comparison
groups (no abortion, unintended pregnancy delivered, pregnancy delivered)
and particular outcomes. A secondary objective was to calculate
population-attributable risk (PAR) statistics for each outcome.
After the application of methodologically based selection criteria and
extraction rules to minimise bias, the sample comprised 22 studies, 36
measures of effect and 877 181 participants (163 831 experienced an
abortion). Random effects pooled odds ratios were computed using adjusted
odds ratios from the original studies and PAR statistics were derived
from the pooled odds ratios.
Women who had undergone an abortion experienced an 81% increased risk of
mental health problems, and nearly 10% of the incidence of mental health
problems was shown to be attributable to abortion. The strongest subgroup
estimates of increased risk occurred when abortion was compared with term
pregnancy and when the outcomes pertained to substance use and suicidal
This review offers the largest quantitative estimate of mental health
risks associated with abortion available in the world literature. Calling
into question the conclusions from traditional reviews, the results
revealed a moderate to highly increased risk of mental health problems
after abortion. Consistent with the tenets of evidence-based medicine,
this information should inform the delivery of abortion services.