There’s an article gaining traction on certain corners of the internet claiming that a confidential Pfizer document revealed that 82 percent of vaccinated pregnant women suffered miscarriage due to the Pfizer Covid-19 vaccine. These claims should draw alarm if they were true. But the report is gravely flawed.

The authors of this claim have made three fundamental errors:

1. They have misinterpreted the Pfizer document to be a comprehensive case report of all outcomes post-vaccination, rather than a list of adverse events only.

2. They have committed the “post hoc ergo propter hoc” logical fallacy, assuming that all adverse outcomes were caused by the vaccine rather than occurring after the vaccine, with unspecified cause.

3. They have committed shockingly bad arithmetic by trying to use numbers of adverse events to determine rates of adverse outcomes.

Reading the conclusions accurately

As a bioengineer and mother concerned about fertility health, I have evaluated the effects of the Covid-19 vaccine on pregnancy and fertility, as well as the Covid-19 disease on pregnant women (as detailed in the Winter 2022 issue of the Human Life Review). So when information arises that suggests the vaccine can hurt women’s fertility or baby health, I take it very seriously.

Let’s walk through the Pfizer data itself to understand what conclusions can and cannot be drawn from it.

The Pfizer document in question (found here) is part of Pfizer’s legal duty to conduct post-market surveillance: to watch for any problems that turn up with the vaccine after it has been released to the market. This particular document is a compilation of all the adverse events reported to Pfizer from various sources across the world, including the U.S.’s VAERS (Vaccine Adverse Events Reporting System). It is not an assessment of whether the vaccine caused those problems, nor can it assess the rates of people experiencing problems. In fact, 100 percent of cases in this document are “problems”—it’s a problem document.

That is not to say that every case in the document is serious. Table 2 lists the events that were reported in more than 2 percent of cases filed. Many of these are mild—fatigue (7,338 events), vaccination site pain (5,181 events), headache (10,131 events), and so on.

Pfizer reports specifically on pregnancy on Table 6 on page 12. Out of the 126,212,580 Pfizer doses shipped as of 28 February 2021 and the 42,086 case reports collected in the same time period, 270 maternal cases were reported, plus 4 fetal/neonatal cases linked to the maternal cases (therefore, pregnancy-related cases were <1 percent of cases reported). The outcomes of those cases are listed below:

To get to an 82 percent miscarriage rate, the authors of the misleading article divided 28 (number of fetal or neonatal deaths reported) by 34 (number of cases with known outcomes), equalling 82 percent.

This calculation is shockingly bad math for several reasons:

1. The “Outcome not provided” and “Outcome pending” cases are not irrelevant. In general, the outcome was likely not provided because the pregnancy was ongoing when the case report was made—the baby was still living.

2. This Pfizer report only includes “cases”—reports where some adverse event occurred. The instigating event may have been mild like headache (33 of the pregnancy cases), injection site pain (24 of the pregnancy cases), or fatigue (22 of the pregnancy cases), or serious like miscarriage and fetal death. This report does not include the many pregnant women and their babies who had completely normal pregnancies and healthy babies following vaccination—it is not the purpose of the adverse event reporting document.

Let me use a metaphor. This poor calculation is equivalent to going to a car repair shop. You count 20 cars—17 are there for repair, 3 cars are picking up a spouse—and calculate that 17/20 = 85 percent of cars are broken down! You also assume the car shop is responsible, because it’s right there!

The correction in the car example is obvious. To calculate the percentage of broken-down cars, you need to know the total number of cars on the road: it is much larger than 20. To understand the cause of the broken-down cars, you need to look at each one: some were in a wreck, some were poorly maintained, and so on.

Likewise, to calculate the miscarriage rate following COVID-19 vaccination, one must use a denominator of all women receiving the vaccine, not just those with adverse events. Many of those studies have been done, and they show no increase in miscarriage rate (defined as fetal death before 20 weeks gestation) following vaccination compared with women who did not receive the vaccine (see extensive discussion in my article in the Winter 2022 issue of Human Life Review). In fact, research published this year shows vaccination is associated with a 15 percent reduction in stillbirth rates (defined as fetal death after 20 weeks gestation) (https://www.nature.com/articles/s41467-022-30052-w) See also https://humanlifereview.com/new-study-shows-covid-vaccine-decreases-stillbirth-by-15/.

The truth about the dignity of human life from the moment of conception is where science is on the side of the pro-life movement. Reporting from pro-life news outlets that gets basic arithmetic and logic wrong undermines pro-lifers’ credibility across all issues and should be taken seriously and corrected. And, at this time, extensive study of the COVID-19 vaccines has continued to show they are safe and effective for pregnant women and their babies.