Pfizer Upholds Commitment to Transparency and Shares Analysis of COVID-19 Vaccination in Pregnant Women

Pfizer Upholds Commitment to Transparency and Shares Analysis of COVID-19 Vaccination in Pregnant Women

NEW YORK, Tuesday, September 9, 2025 - Pfizer Inc. (NYSE: PFE) today posted COVID-19 vaccine data in pregnant women, continuing to deliver on President Trump's call for transparency of our findings in an open and accessible manner. A summary of clinical and real-world evidence published in Pfizer's COVID-19 updates and research hub provides the following findings:

• Available data show that effectiveness of mRNA COVID-19 vaccines is similar in pregnant and nonpregnant women of similar age for prevention of SARS-CoV-2 infection and hospitalizations. Maternal COVID-19 vaccination during pregnancy reduces the risk of SARS-CoV-2 infection and COVID-19-associated hospitalization in infants younger than 6 months of age. Additionally, COVID-19 vaccination may help prevent stillbirths and preterm delivery, which are notably higher in infected populations.^1,2,3
• Prior to conducting clinical trials in women of childbearing potential, including pregnant women, Pfizer completed a developmental and reproductive toxicity (DART) study with the vaccine, which was required by the regulatory authorities before starting the study in pregnant women. Those studies showed no evidence of fertility or reproductive toxicity in animals.⁴
• A global Phase 2/3 placebo-controlled randomized study evaluated the safety, tolerability, and immunogenicity of the COVID-19 vaccine in healthy pregnant women 18 years or older. Data from the study, shared publicly⁵ and also shared with the U.S. Food and Drug Administration (FDA) and global regulatory authorities, suggest the vaccine is well-tolerated by both mothers and infants and supports a favorable benefit risk profile in pregnant women. As part of the study, participants received a COVID-19 vaccine or placebo at 24 to 34 weeks of gestation. The study found congenital anomalies reported in 8 out of 156 vaccinated [controlled arm] participants and 2 out of 159 unvaccinated [placebo] participants. This incidence is within the range observed in the general population, and events were not deemed to be vaccine related.⁵ Likewise research by an independent group using a multinational real-world evidence analysis involving 343,066 infants, found COVID-19 vaccination during the first trimester, the time period when most congenital malformation occur⁶, was not associated with the risk of congenital anomalies.⁷
• Furthermore, a comprehensive analysis from 177 studies with data from 638,791 pregnant women observed statistically significant reductions in stillbirth and emergency caesarean deliveries with mRNA vaccines administered during the pregnancy.⁸
• In the 130 countries where the vaccine is available, no label includes a contraindication for pregnant women.

"The safety of our vaccines remains our top priority," said Chris Boshoff, MD, PhD, Chief Scientific Officer and President, Research and Development at Pfizer. "COVID-19 infection poses risks to newborns and pregnant women, and we are committed to monitoring and reporting these outcomes. We continue to uphold the highest standards of safety, transparently sharing trial data to maintain the trust of patients, health authorities, and the public."

In late 2021, Pfizer shared enrollment of its global Phase 2/3 study was stopped. This study was developed prior to availability or recommendation for COVID-19 vaccination in pregnant women. By September 2021⁹, COVID-19 vaccines were recommended by applicable recommending bodies (e.g., ACIP in the U.S.) for pregnant women in all participating/planned countries, and as a result the enrollment rate declined significantly. With the declining enrollment, the study had insufficient sample size to assess the primary immunogenicity objective and continuation of this placebo-controlled study could no longer be justified due to global recommendations. This proposal was shared with and agreed to by the U.S. FDA and European Marketing Authorization.

About Pfizer: Breakthroughs That Change Patients' LivesAt Pfizer, we apply science and our global resources to bring therapies to people that extend and significantly improve their lives. We strive to set the standard for quality, safety and value in the discovery, development and manufacture of health care products, including innovative medicines and vaccines. Every day, Pfizer colleagues work across developed and emerging markets to advance wellness, prevention, treatments and cures that challenge the most feared diseases of our time. Consistent with our responsibility as one of the world's premier innovative biopharmaceutical companies, we collaborate with health care providers, governments and local communities to support and expand access to reliable, affordable health care around the world. For 175 years, we have worked to make a difference for all who rely on us. We routinely post information that may be important to investors on our website at https://www.Pfizer.com. In addition, to learn more, please visit us on https://www.Pfizer.com and follow us on X at @Pfizer and @Pfizer News, LinkedIn, YouTube and like us on Facebook at Facebook.com/Pfizer.

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1Prasad, S., Kalafat, E., Blakeway, H. et al. Systematic review and meta-analysis of the effectiveness and perinatal outcomes of COVID-19 vaccination in pregnancy. Nature Communications. (2022). https://www.nature.com/articles/s41467-022-30052-w2Fleming-Dutra et al. Safety and Effectiveness of Maternal COVID-19 Vaccines Among Pregnant People and Infants. Obstetrics and Gynecology Clinics of North America. (2023). https://www.sciencedirect.com/science/article/pii/S0889854523000372?via%3Dihub3Centers for Disease Control and Prevention. (n.d.). COVID-19 vaccination for women who are pregnant or breastfeeding. Centers for Disease Control and Prevention. https://www.cdc.gov/covid/vaccines/pregnant-or-breastfeeding.html?CDC_AAref_Val=https://www.cdc.gov/coronavirus/2019-ncov/vaccines/recommendations/pregnancy.html4Bowman, C. et al. Lack of effects on female fertility and prenatal and postnatal offspring development in rats with BNT162b2, a mRNA-based COVID-19 vaccine. Reproductive Toxicology, (2021). https://www.sciencedirect.com/science/article/pii/S0890623821000800?via%3Dihub5ClinicalTrials.gov. (n.d.). Study details: NCT04754594, to evaluate the safety, tolerability, and immunogenicity of BNT162b2 against COVID-19 in healthy pregnant women 18 years of age and older. ClinicalTrials.gov. Accessed September 8, 2025. https://clinicaltrials.gov/ct2/show/NCT047545946Centers for Disease Control and Prevention. (n.d.). About birth defects. Centers for Disease Control and Prevention. Retrieved September 8, 2025, from https://www.cdc.gov/birth-defects/about/index.html7Magnus et al., COVID-19 infection and vaccination during the first trimester and risk of congenital anomalies: Nordic registry-based study. British Medical Journal. (2024) https://www.bmj.com/content/386/bmj-2024-0793648Ciapponi, A. et al. Safety and Effectiveness of COVID-19 Vaccines During Pregnancy: A Living Systematic Review and Meta-analysis. Drug Safety. (2024) https://link.springer.com/article/10.1007/s40264-024-01458-w 9Centers for Disease Control and Prevention. "CDC issues urgent health advisory recommending COVID-19 vaccination during pregnancy." Sept. 29, 2021. https://archive.cdc.gov/www_cdc_gov/media/releases/2021/s0929-pregnancy-health-advisory.html

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