That is credible.
And of those 400K abortions, I would bet a high percentage of those were in states where it was already legal (a better comparison would be limit the states to where it was illegal prior to Roe…Roe changed nothing where it was already legal.
Well, so much for the theory that there is no correlation between the abortion rate of a population and the criminality of abortion.
It is “credible”, because it is what you already want to believe. But the number is essentially made up. The history is that pro-life groups were widely citing a study from 1981 that statistically calculated the number of illegal abortions pre-Roe v. Wade as 68,000 to 443,000, with a median estimate of 210,000 per year. Most folks used the 68-210, but never mentioned the 400+. However, scientific peers noted that the study could not be reconcilled with census data and some assumptions were challenged and the authors acknowledged that their numbers are undoubtedly flawed. Since then, you see the high number from the study pop up a lot, but it is just a number, pulled out of thin air - much like the 40 million, 50 million, etc. you just threw out earlier.
Most studies place the numbers significantly higher, but still are not very compelling. There just isn’t much data. Note that the Guttmacher institute, which I linked to above, won’t even cite illegal abortion data, merely noting that the studies vary wildly.
Some of the most compelling data comes from the late 1800’s and pre-1950 census data. Again, when just counting death certificates turns up thousands of abortion related deaths in a single year in the 1940s, it is clear that the greatest generation had reproductive issues as well. Compare that with the 200 or so just prior to Roe v. Wade (you’ll see the number 39 a lot, but that only includes the CDC Abortion Surveillence project, which focussed on legal abortions and did not utilize some sources prior to 1977, and still under reports abortions, for example in 2000 it reported just 847,000 abortions, but most research places the number closer to 1.2M for the same year).
However, even if we pretended that the made up number had any basis in reality, it, in of itself, cannot really prove anything. That is because the demographics of the country is not static, but runs in cycles. The most meaningful comparison of abortion rates is not total numbers, since even total population numbers, but what is called the incidence rate, often expressed as the number of abortions per 1,000 women aged 15-44 (child bearing years).
The legal rate in the US was 16 pre-Roe v. Wade. It is 21 now. It soared to 29 in 1979 and has been decreasing ever since. We have observed from multiple studies for over a decade that the number is lower, on average, in countries with permissive abortion and contraception laws than in countries that have very stringent laws on both.
This has led to speculation that permissive secular laws actually reduce abortions. A thought that makes some conservative heads explode. What makes the recent study interesting is that a lot more information was indirectly collected from various record sources. This allowed the data to be compared in different ways not previously possible.
What the researchers found was that no statistical correlation could be found between legalization of abortion and the lower incidence rates. That is, they disproved the simple bigger>smaller comparison that seemed to support a pro-aboriton talking point. However, they did find a statistical correlation with poverty and one with access to contraception.
No significant theories as to why correlations exist or do not exist was presented. The study just collected a massive amount of additional data and showed that statistical correlations exist. Why there is are connections are subjects for further study.
If your idea of science is to take a made up number that sounds right to you and compare it to another number, with no regard for total populations or demographics, all the steps in trying to calculate the world as it actually is probably sounds pretty tedious. But that is the way science works.