Why abortion numbers are difficult to obtain – and are often unreliable

(Secular Pro-Life) Collecting accurate figures about the incidence of abortion is remarkably difficult. This is the case not only in countries where abortion is illegal, but also in those where the practice is legal but the healthcare system either can not or does not want to provide accurate figures. Generally speaking, no country with a low or medium Human Development Index (i.e. below 700) keeps accurate official registries of the incidence of abortion.

In order to remedy this shortcoming, several methods have been developed for estimating the incidence of abortion. The two most broadly used methods were developed by pro-choice organizations. The residues method (also known as proximate determinants of fertility framework) 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

Residues method yields very high figures.

The residues method, developed by John Bongaarts, involves using a complex equation including possible fertility (the total number of children a woman would be able to have along all her life should she not use any family planning method nor had any fertility issues), the contraceptive prevalence rate, and other data in order to get an abortion rate/ratio. The main point is that Bongaarts’ method is extremely likely to yield very high abortion rates/ratios. For example, the residues method gave a figure of around 500,000 abortions in Argentina for 2005.

AICM also produces alarmingly high estimates.

The Abortion Incidence Complications Method (AICM) is simpler, but the bias takes a different form. This method takes the figure of women treated for complications of induced abortions and then uses an estimated multiplier for the number of abortions corresponding to every hospitalization. The multiplier is calculated by making a survey of “public health experts.” This item does not include just obstetricians, gynecologists and doctors in general, but also people like “community activists” or “activists of women’s organizations,” which looks much like a code word for pro-choice activists. Moreover, given the current polarization regarding the abortion issue, the recruitment of a research team without a bias in one sense or the other is quite difficult.

The complications method has resulted in alarmingly high estimates. For example: around 800,000 abortions in 2006 and around 1,000,000 in 2009 for Mexico (44 abortions/100 births). For Pakistan, an estimation of 2.2 millions in 2012 (41 abortions/100 births) was given. For Colombia, the estimated figure was 400.000 (56 abortions/100 births) in 2008. The same exaggerated figures are given for almost every country where abortion is illegal, regardless of their social, economic or cultural features.

Actual figures turn out to be vastly lower than Residues and AICM estimates.

Very often, when abortion is legalized, it emerges that the real figures for the incidence of abortion were less than a third or even less than a seventh of the previous estimations.

For example, in 2006 the AICM estimated 165,000 abortion in Mexico. After abortion was made legal in Mexico City in 2007, the number of abortions performed in government-run hospitals was less than 20,000 a year (data about abortions from private healthcare providers are not available, but given the level of widespread reliance on government-run healthcare in Mexico, the figure should be lower).

Similarly, in 2005 the Residues method estimated 500,000 abortions in Argentina. Abortion was legalized in Argentina in 2020, and in 2021 and 2022, the first two years in which the practice was legal, actual figures were 73,487 and 96,664, for each year.

Other methods of estimating

Other methods which are less used involve interviewing people close to post-abortive women, using probabilistic samples, the so-called “confidante method.” The reliability of this method is compromised by the controversial nature of the issue and the influence which the attitude towards abortion or experiences with it could have…

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Editor’s Note: This article was published at Secular Pro-life and is reprinted here with permission.