Fact check: Misinterpretation leads to false claim about Pfizer’s COVID-19 vaccine and pregnancy

Chris Mueller, USA TODAY
·5 min read
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The claim: 44% of pregnant women who participated in a Pfizer COVID-19 vaccine trial had miscarriages

Multiple studies have found people who received a COVID-19 vaccine just before or during early pregnancy were not at increased risk for miscarriage, according to the Centers for Disease Control and Prevention.

But a claim spreading online warns that 44 percent of pregnant women who participated in a Pfizer COVID-19 vaccine trial suffered miscarriages.

The claim was first published by the Daily Clout, a website run by author Naomi Wolf, who last year was suspended from Twitter after spreading vaccine-related misinformation. The article, which has since been deleted, cited a 3,600-page document it claimed revealed that 22 of 50 women who became pregnant during a Pfizer vaccine trial had miscarriages.

“According to Dr. Naomi Wolf, who runs a crowdsourced project to analyze 300,000 Pfizer documents released via a FOIA request, 44 percent of pregnant women who participated in the drug maker’s COVID-19 vaccine trial lost their babies,” reads an Aug. 16 Facebook post by PragerU social media influencer Will Witt that was shared more than 300 times.

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But the claim is based on a misinterpretation of the vaccine trial document, Jeffrey Morris, a biostatistics professor at the University of Pennsylvania’s Perelman School of Medicine, told USA TODAY.

Morris examined the document and found that the article's conclusion was based on "numerous mistakes," including counting individual patients multiple times.

USA TODAY reached out to the website and several users who shared the claim for comment.

Getting vaccinated on Sept. 9, 2022, in Chicago.
Getting vaccinated on Sept. 9, 2022, in Chicago.

Studies show COVID-19 vaccines are safe for pregnant people

The Daily Clout article misinterprets the vaccine trial document by failing to check the unique numbers used to identify patients for duplicate reports of miscarriages, Morris said.

There are 13 patients who reported miscarriages, he said, but nine of those patients are duplicated in the document, leading to the article's incorrect count. Nothing in the vaccine trial document shows that the vaccine was the cause of the miscarriage.

Out of those 13 patients, Morris pointed out that only three are also listed among the 50 patients who reported being pregnant after getting the first dose of the vaccine.

In a statement to USA TODAY, Pfizer said its COVID-19 vaccine "has been shown to be safe and effective for pregnant women and is recommended by global health organizations and regulatory agencies around the world."

Pfizer added that "numerous peer-reviewed studies and real world evidence have demonstrated that the (vaccine) is safe and effective."

In general, miscarriages occur in about 10 percent to 20 percent of all pregnancies, though the overall risk depends on a variety of factors, including the age of the pregnant person and other health conditions, Dr. Ruth Lathi, a professor of obstetrics and gynecology at Stanford University, told USA TODAY.

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Lathi said it's important to note that Pfizer's vaccine trial was not designed to look at pregnancy health.

“Since it wasn’t a study designed for pregnancy, they weren’t asking about healthy pregnancies, they were just asking about adverse events," she said.

Many large studies addressing the question of vaccine safety and pregnancy have already been published and peer-reviewed, Lathi said.

“Unequivocally, several studies have confirmed that there are no adverse events in pregnancy associated with the vaccine,” she said.

Studies have shown that pregnant people are at increased risk of developing severe COVID-19 if they are infected, according to the World Health Organization, which lists getting vaccinated among its recommendations for pregnant people hoping to avoid a COVID-19 infection.

The CDC says COVID-19 vaccines received during pregnancy reduce the risk of a severe illness, citing recent studies that compared pregnant people who got the vaccine with those who did not.

USA TODAY has previously debunked other false claims that the vaccines cause miscarriages, as well as baseless assertions that women who are pregnant or breastfeeding shouldn't get the shot and exposure to a vaccinated person can cause women to miscarry or experience menstrual changes

The Associated Press and Reuters also debunked the claim.

Our rating: False

Based on our research, we rate FALSE the claim that 44 percent of pregnant women who participated in Pfizer's COVID-19 vaccine trial had miscarriages. The figure is based on a misinterpretation of a Pfizer vaccine trial document. Multiple peer-reviewed studies have found people who received a COVID-19 vaccine just before or during early pregnancy were not at increased risk for miscarriage.

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This article originally appeared on USA TODAY: Fact check: False claim about Pfizer’s COVID-19 vaccine and pregnancy