Abortion statistics are not always accurate and are sometimes unreliable

The correct numbers in regards to abortion cases is a subject that is incredibly difficult to gather information on. This difficulty is unfortunately not exclusive to countries that have criminalised abortion. It is also common that, in countries where abortion is legal, the healthcare system refuses to disclose the accurate figures or is not permitted to do so.

There have been many methods developed to estimate the occurrence of abortion in order to make up for the lack of solid answers. Two of the most popular methods used were created by pro-choice organisations. The residues method was developed in 1982 by Population Council’s researcher John Bongaarts and the Abortion Incidence Complications Method (AICM) was developed by the Guttmacher Institute in the early 1990s

John Bongaarts invented the residues method which involves using a complex equation that takes into consideration possible fertility (this is the number of children a woman could have in her lifetime if she were to not use any family planning method or so long as she doesn’t have any fertility issues), the contraceptive prevalence rate, and other data in order to achieve the average abortion rate. The goal of Bongaarts’ residues method is to obtain accurate data on the very high abortion rates. For example, the residues method gave a figure of around 500,000 abortions in Argentina for 2005.

Though it is biased in a different way, the Abortion Incidence Complications Method (AICM) is far easier. This method works by taking the number of women hospitalised for complications resulting from induced abortions and then using an estimated multiplier for the number of abortions corresponding to each hospitalisation. One method of calculating the multiplier is to survey "public health experts." This term covers not only obstetricians, gynaecologists, and doctors, as one may assume, but also "community activists" and "activists of women's organisations," which appear to be code words for pro-choice activists. Furthermore, it is a challenge to assemble a research team free from prejudice in any kind given the existing division surrounding the abortion debate.

When abortion is legalised, it is frequently discovered that the true figures for abortion cases were less than a third, if not less than a seventh, of the earlier estimates. 

The AICM, for example, predicted 165,000 abortions in Mexico City in 2006. Following the legalisation of abortion in Mexico City in 2007, the number of abortions performed in government-run hospitals was less than 20,000 per year. 

Other, less common techniques include the so-called "confidante method," which involves questioning friends and family of women who have had abortions and using probabilistic sampling. Because of the topics controversial nature and the potential impact of individuals attitudes towards or experiences with abortion jeopardise the validity of this approach. 

Recently, a team of academics, led by sociologist Jonathan Bearak and associated with the medical journal The Lancet and the Guttmacher Institute, came up with what they describe as a new method for calculating the prevalence of unplanned pregnancy and abortion. The model is based on an equation that includes factors such as the rate of unmet contraceptive needs, contraceptive failure, and nuptiality, among others. The Guttmacher Institute recently released a publication based on this study. 

Chilean doctor Elard Koch invented the two mainly used methods for estimating information on abortion. The first method is quite similar to the AICM method, however Koch's estimate of the incidence of spontaneous abortion, or miscarriage, is higher than that of pro-choice researchers. Women admitted to hospitals due to miscarriage problems were frequently counted as having induced abortions rather than miscarriages under the AICM. The estimation of abortions significantly declines using Koch's method because women hospitalised for postpartum problems were more likely to be recorded as having actually experienced miscarriages. 

Finally, we must mention the main estimation methods used until now by pro-life researchers: specifically the ones developed by Chilean doctor Elard Koch. Koch developed two methods. 

The first is similar to the AICM, but the difference is that Koch estimates the incidence of spontaneous abortion (miscarriage) at a higher level than pro-choice researchers had estimated. Under the AICM, women hospitalised for complications of miscarriage were often counted as having induced abortions rather than miscarriages. Under Koch’s method women hospitalised for complications of miscarriages were more likely to be counted as having actually had miscarriages, so the estimation of abortions decreases considerably. 

The second Koch technique entails applying the abortion statistics from 1987 for Spain to other countries. Koch assumes that the first year for which official, trustworthy abortion statistics were available for Spain was 1987.

The numbers obtained from both methods are remarkably low, with abortion ratios ranging from 5 to 10 per 100 live births. In the first approach, Koch substitutes his own estimate of the likelihood of a spontaneous abortion for the official hospitalisations. Koch ignores the fact that the abortion legislation in effect in Spain was vaguely drafted regarding the grounds for permitting abortions when using the second method. Because they were unsure of the procedures' legality, many private healthcare providers did not fully report the abortions they performed until the 2000s. Reporting issues, rather than an increase in the incidence of abortion, can account for, at least partially, the rise in abortion statistics between 1985 and 2010. 

As it is nearly impossible to collect accurate figures on the incidence of abortion in countries where it is illegal or the healthcare system does not provide them, ideologically biased estimates are likely to be made. Perhaps in a less divided political environment on the subject of abortion, more reliable and effective methods of estimation could be developed and used.

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Photo credit: Andrii Yalanskyi / Shutterstock

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