We came across this post on Facebook:

According to the post which contains a link to an article by the Florida Standard, 44 percent of pregnant women participating in Pfizer’s mRNA COVID vaccine trial suffered miscarriages.

The article arrived at this figure by citing a sprawling 3,645-page document that was first released on 1 July 2022 via the Public Health and Medical Professionals for Transparency Documents (PHMPT) website . The document, listing adverse events reported during Pfizer’s clinical trial, was part of Pfizer’s submission to the FDA Center for Biologics Evaluation and Research (CBER) in order to introduce the product into interstate commerce.

When we conducted a search on the claim, we found that established factcheckers Reuters and Health Feedback had recently taken a look at the study, describing the data cited in the claim as being misrepresentative and factually inaccurate.

Flawed Calculations?
In the original claim, 22 of the 50 pregnant women who had taken part in the clinical trial had suffered from miscarriages. However, looking at the data presented in the document, this number is incorrect as the numerator (22 miscarriages) is overstated as it includes duplicated participant case numbers, while the denominator (50 pregnant women) is inaccurate as well.

Tony Panzarella, Program Director, MSc in Biostatistics at the Dalla Lana School of Public Health, University of Toronto informed Reuters in their factcheck that “the reported 44% (22/50) estimated percentage of subjects experiencing a miscarriage is incorrect.” The numerator was found to have included multiple duplicates.

For example, case number C4591001 1013 10131255 appears on both pages 219 and 3,519-3,520, and case number C4591001 1231 12313998 appears on both pages 1,806 and 3,551.

Secondly, among the subjects identified as having had miscarriages or spontaneous abortions, “the majority were not part of the 50 subjects that comprise the denominator,” Panzarella said.

For example, case identifier C4591001 1013 10131255, as mentioned above, is not included in the table on pages 3,643-3,644.

Safe for Pregnant Women?
Having looked at the data presented, the 44% figure in the claim purporting to represent the percentage of pregnancies lost among participants in the Pfizer COVID-19 vaccine trial is inaccurate and misrepresented. The author failed to account for duplicate listings and underestimated the total number of pregnancies. Additionally, the original post has since been flagged by Facebook as having false information due to independent fact-checkers finding that the information present in the claim has no basis in fact.