Senator Ted Cruz, R-Texas, has again faced criticism for promoting a debunked statistic regarding the COVID-19 vaccine and its alleged risk of miscarriage in pregnant women. Cruz shared a preview of an upcoming podcast episode with Ben Ferguson, stating, "We now have the receipts: Dr. Fauci and Pfizer knew the second dose of the COVID vaccine carried an 82% risk of miscarriage for women in their first trimester."
This claim has been refuted by infectious disease experts and maternal-fetal medicine organizations. The Society for Maternal-Fetal Medicine, an organization representing high-risk pregnancy experts, has previously stated that research shows "no increased risk for miscarriage, preterm delivery… from COVID-19 vaccination during pregnancy."
Cruz's recent comments follow the release of text messages from January 2021, reportedly between Dr. Anthony Fauci, former CDC Director Rochelle Walensky, and former U.S. Surgeon General Vivek Murthy. In these messages, Fauci expressed that the COVID-19 vaccine "theoretically could be associated with miscarriage in the 1st trimester" around the same time he publicly stated there were "no red flags" for pregnant women receiving the vaccine.
This is not the first time Cruz has made claims about the COVID-19 vaccine's safety for pregnant individuals. During a Joint Economic Committee hearing in April 2021, Cruz questioned infectious disease physician Dr. Celine Gounder. Gounder, who served on the COVID-19 advisory board during the Biden administration, disagreed with Cruz's assertion that pregnant women were not advised to get vaccinated. Economist Alexander Tabarrok also corrected Cruz at the time, stating, "The recommendation actually is that pregnant women are — should be vaccinated."
Dr. Gounder told HuffPost that she provided Cruz's committee with evidence in April 2021, including a study from The New England Journal of Medicine (NEJM) that she believes is the source of Cruz's 82% statistic. The NEJM study, published in April 2021, analyzed data from the CDC's V-safe pregnancy registry. Of the 3,958 pregnant women in the study, 827 completed their pregnancies during the study period, resulting in live births, miscarriages, or other outcomes.
The 82% figure cited by Cruz appears to stem from a misinterpretation or miscalculation within a reader's argument in a now-deleted letter to NEJM. This argument suggested excluding participants vaccinated in the third trimester, leading to a recalculated risk. Gounder explained that this method disregarded a significant portion of the study's participants. The NEJM study's authors noted that early data collection in pregnancy-safety research can sometimes oversample pregnancy losses.
A follow-up analysis by the CDC in September 2021 further addressed and disproved the 82% theory. This study followed 2,456 women vaccinated before or early in their pregnancy. The reported miscarriage rate in this study was 14%, which falls within the generally accepted average miscarriage rate of 11% to 22% for pregnancies.
Regarding Fauci's private text messages, Gounder suggested they reflected a need for discussion among health officials because drug manufacturers had excluded pregnant women from initial COVID-19 vaccine trials. This meant there was no trial data available for pregnant individuals at that time.
The 82% statistic has resurfaced in other contexts, including testimony before the Senate Permanent Subcommittee on Investigations in May 2023 by Florida gynecologist Dr. James Thorp. Thorp presented data he claimed showed an 82% miscarriage rate in women vaccinated during the first trimester, using a similar recalculation method applied to the NEJM study data.
When Senator Ron Johnson, R-Wis., published Fauci's texts, his statement referenced Thorp's testimony. The statistic has since been amplified by various right-wing media outlets and political figures.
Cruz's mention of Pfizer likely refers to a voluntary safety report from April 2021, which logged 270 self-reports of adverse vaccine effects from pregnant individuals. Of the 32 cases where pregnancy outcomes were reported, 26 involved a miscarriage, resulting in an approximate 81% rate. However, experts note this data is unreliable due to the small number of participants who provided follow-up information and the lack of rigorous methodology.
Leading medical organizations continue to recommend COVID-19 vaccines for pregnant individuals. The American College of Obstetricians & Gynecologists (ACOG) states that "COVID-19 vaccine safety during pregnancy has been well established" and recommends vaccination for those contemplating pregnancy, recently pregnant, or lactating. A 2024 study cited by ACOG found no association between COVID-19 mRNA vaccination during pregnancy and increased risks of pregnancy loss, including in the first trimester.