Background
Research regarding the mental health effects of abortion has been plagued by political controversy and selective reporting of results.[1] One frequently cited study in this field is an analysis of Danish medical records which reported a 127% elevated risk of first-time treatment for psychiatric disorders among women following a first induced abortion (15.2 cases per 1000 person years, 95% CI: 14.4 to 16.1) as compared to women having a first live birth (6.7 cases per 1000 person years, 95% CI: 6.4 to 7.0).[2] Despite this finding of higher rates of mental health care following abortion, the authors concluded that abortion does not increase the risk of mental illness based on their additional analyses of first-time contact for psychiatric treatment in the nine months prior to these pregnancy outcomes. Based on those analyses, the authors concluded that the women who are most likely to have abortions were simply at greater risk of first-time psychiatric treatment contact prior to their abortions, and therefore the elevated rate of mental health issues observed after abortion is simply an incidental continuation of pre-existing mental health risks. In short, they suggested, women who are predisposed to mental health issues are more likely than others to have abortions. Therefore, their main finding of higher rates of mental health disorders among aborting women, as compared to delivering woman, can and should be ignored; abortion has no independent mental health effects.
This study was widely criticized for several methodological issues. For example, similar records-based studies of mental health treatment rates before and after abortion had controlled for twelve months of prior mental health[3,4] whereas the Danish study inexplicably examined only nine months. The selection of nine months prior to the pregnancy outcome also meant that they were comparing women who carried to term during only the time they were pregnant to women who had abortions who were only pregnant for approximately two to three months prior to their abortions and were not pregnant during the other six months. A better methodological baseline, as used in other studies, would have been to control for mental health history for a full year prior to conception of the index pregnancy. Moreover, while the prior studies had excluded women with a history of abortion from the control group of women who carried to term, the Danish study included women with one or even multiple abortions into the group of delivering women once they had a first live birth. In other words, they were comparing women who had a first abortion against a mixed group of women who had one or more abortions prior to their first live birth, women who had miscarriages prior to a first live birth, and women whose first pregnancy ended in a first live birth. This admixture would clearly tend to obscure rather than clarify the interpretation of their findings. A request sent to the lead author (Munk-Olsen) for a breakdown of the number of first-time mental health treatment cases in the delivery group based on prior exposure to abortions by the author of this reanalysis was refused. In my experience, that refusal was atypical. When I have made similar queries of other authors, they have been quick to provide such clarifications of their findings. An additional shortcoming is that unlike prior studies,[3,4] the Danish study failed to segregate their results relative to inpatient and outpatient treatments, even though this would have been an excellent way to distinguish between the severity of mental illnesses. Yet another problem was that the researchers chose to exclude women who died during the year following their pregnancy outcomes, which is problematic since abortion is associated with increased rates of suicide and deaths from other self-destructive behaviors, which are clearly markers of psychiatric distress.[5] Finally, in addition to using a shorter pre-abortion period of investigation, the investigators limited their post-abortion period to just one year. This was another step back from the methodological strength of the prior record-linkage studies that examined treatment rates over a period of four years following an index pregnancy outcome.[3,4] A longer period of follow up is important in consideration of the literature indicating that the most severe reactions to abortion can be delayed until after coping mechanisms are exhausted and may be related to anniversary reactions and other triggers such as a subsequent pregnancy.[6–10] By limiting the investigation to one year, the Danish research team would likely miss some of the reactions associated with the one year anniversary, if they fell just outside the anniversary date, in addition to any other delayed reactions.
The Danish researchers’ conclusions have also been called into question by both prior studies which employed better methodologies,[3,4] and subsequent studies.[11–14] For example, an analysis of the National Longitudinal Study of Adolescent to Adult Health (Add Health) which controlled 25 confounding factors, including prior mental health and exposure to violence, found that each exposure to abortion increased the risk of subsequent mental health disorders, a finding that could not be explained by prior mental health.[11] In addition, the subset of women who reported aborting a wanted child experienced a 122% higher rate of depression and a 244% higher rate of suicidality.[14]
Two other studies, based on medical records of nearly 5,000 women continuously covered by Medicare from the age of 16 forward, examined mental health treatment rates both prior to and after each woman’s first pregnancy outcome.[12,13] These studies found that the change in the rate of mental health treatments per patient per year from before to after a first pregnancy outcome was highest among women who had abortions, compared to both women who carried to term[12] and women who had natural losses.[13] This was also true for both outpatient treatments and inpatient treatments. It was also true relative to the length of hospitalization for inpatient care, which is an excellent marker for a difference in the severity and complexity of mental health issues.
Given the discontinuity between the Danish authors’ conclusions and the findings of prior and subsequent studies of a similar nature, the purpose of this reanalysis is to determine if the Danish data can be reconciled with the direction of findings of other studies over the full time period of the data presented.