A study examining 17 years of patient data has found absolutely no evidence that having an abortion increases the risk of suicide, despite many women being told the opposite.

Examining years of data collected from over half a million women in Denmark, researchers conclude that heightened suicide attempts are not caused by abortion. Instead, pre-existing health issues, like the use of psychiatric services and anti-depressants, are far better at predicting suicide risks.

"The view that having an abortion leads to suicidal thoughts, plans, or even suicide attempts has been used to inform abortion policies in some regions of the world, particularly laws requiring women seeking the procedure be informed of this view," says reproductive health scientist Julia Steinberg from the University of Maryland.

"The evidence from our study does not support this notion."

Nevertheless, in many places, doctors are obliged to tell patients unvalidated information about abortion's negative psychological or emotional effects, which can include that it increases the risk of having suicidal thoughts.

The warning is based on studies fraught with limitations and flaws, and in recent years, several researchers have tried to reproduce these findings with more rigorous methods.

Instead of looking simply at mental health after an abortion, the new studies compared mental states before and after, while also accounting for histories of psychiatric illnesses and other confounding factors.

Last year, a five-year analysis of nearly 1,000 women found that levels of suicidal ideation were similarly low among those who had abortions and those who were denied abortions.

At the same time, it also revealed that women who seek abortions at a later gestational age are at no higher risk of suicidal thoughts. Instead, the authors say a history of mental health conditions and intimate partner violence are much more predictive.

"Policies requiring women to be warned that they are at increased risk of becoming suicidal if they choose abortion are not evidence based," the study concluded.

Other reviews on the safety and efficacy of abortion have also found it does not increase the risk of depression, anxiety, or post-traumatic stress.

The most recent research from Denmark draws upon a particularly long data bank with its 17 years' worth of patient records, and it once again agrees with the previous results. Using data from national patient registries, it examined non-fatal suicide attempts and self-harm among women with first-time abortions in the first trimester.

Unlike previous research, which failed to consider prior mental health issues and the downsides of self-reporting on abortion and suicide, the new study follows its patients from the year before the abortion to the year after.

Adjusting for age, year, the history of childbirth, mental health, physical health, and socioeconomic status, the team concluded abortion could not be causing or increasing the risk of suicide attempts.

"When we examined the monthly incidence rates of suicide attempts in the year before and after an abortion for all women who had an abortion," the authors write, "women with a previous psychiatric contact, and women with no previous psychiatric contact, we found no changes in incidence rates from the year before to the year after the abortion for all three groups."

To be fair, the study did not look at the effect of later abortions or multiple abortions on mental health, but the findings suggest that at least in the case of early first abortions, suicide is not a risk stemming from the procedure.

The authors argue any policies based on that notion are therefore "misinformed". 

"The increased risk of non-fatal suicide attempts in women who have had an abortion might be related to other co-occurring risk factors around the time of the unwanted pregnancy and abortion, such as intimate partner violence, unstable relationships, or other negative life events, for which Steinberg and colleagues could not adjust," explains social and behavioural scientist Jenneke van Ditzhuijzen from the University of Amsterdam in the Netherlands, who was not involved in the study but is the author of a commentary published alongside it. 

"This does not mean that having an abortion is an indication that women are going through a difficult time, or that the symptoms of mental disorders are attributable to the abortion, but rather that some women are at an elevated risk of multiple adversities at a certain period in their life, which could include an unwanted pregnancy and abortion." 

The study was published in The Lancet Psychiatry.