Maternal vaccination not associated with increased risk of serious adverse events or negative pregnancy outcomes.
FOR IMMEDIATE RELEASE
May 13, 2026
MINNEAPOLIS, Minn. — The Vaccine Integrity Project’s comprehensive review of peer-reviewed evidence on tetanus, diphtheria, and acellular pertussis (Tdap) vaccination during pregnancy finds that the vaccine provides critical protection to infants during the first months of life when they are most vulnerable to whooping cough. The data did not indicate that receiving Tdap during pregnancy increased the risk of serious adverse events or a host of negative pregnancy outcomes that were evaluated by researchers.
The systematic review and meta-analysis screened more than 14,000 papers and evaluated 91 studies, including 29 studies included in previous systematic reviews and 62 new studies published through March 2026. The analysis incorporated evidence from randomized controlled trials and large observational studies. The most recent ACIP publication reviewing Tdap vaccine evidence was the Morbidity and Mortality Weekly Report “Use of Tetanus Toxoid, Reduced Diphtheria Toxoid, and Acellular Pertussis Vaccines,” published in January 2020, which summarizes available evidence (including safety outcomes) and policy for Tdap use. The report reflected evidence considered through late 2019. The recommendation to give Tdap during every pregnancy was last formally reviewed and voted on by ACIP in October 2012.
The findings from the Vaccine Integrity Project, an initiative of the University of Minnesota’s Center for Infectious Disease Research and Policy, working with the nonprofit Evidence Foundation, reinforce longstanding evidence that maternal Tdap vaccination helps prevent pertussis infection and serious complications in young infants.
Pertussis remains a persistent public health concern in the United States, particularly for infants too young to begin routine vaccination. In 2025, more than 28,000 cases were reported nationwide, with the highest rates of severe illness and death occurring in infants under one year of age. Maternal vaccination during pregnancy provides antibodies that are passed to the infant before birth, offering protection during the vulnerable period before childhood vaccination with DTaP is recommended.
The Vaccine Integrity Project review found no evidence linking Tdap vaccination during pregnancy to a meaningful increase in the risk of adverse maternal or infant outcomes. Across a wide range of outcomes, including stillbirth, preterm birth, eclampsia and preeclampsia, gestational diabetes, congenital anomalies, and neonatal complications, rates were similar among vaccinated and unvaccinated populations.
These findings are based on a large and diverse body of evidence. While estimates from individual studies are sometimes imprecise – often related to low baseline risk of outcomes, such as congenital anomalies – the overall pattern across studies was consistent and reassuring, especially paired with continuous safety monitoring across multiple systems that are designed to find rare adverse events.
In addition to the absence of safety findings, the review found that Tdap vaccination during pregnancy provides substantial protection for infants. Maternal vaccination was associated with probable reductions in pertussis infection and in severe disease, including hospitalization. Evidence also suggests protection against pertussis-related infant death, though such outcomes are rare. That protection is consistent with the immune responses found in both pregnant women and infants. Vaccination during pregnancy leads to higher maternal antibody levels at delivery, and infants born to vaccinated pregnant women have elevated antibody levels at birth, supporting protection until they begin their routine DTaP vaccination series at two months of age.
“As clinicians and policymakers consider vaccine recommendations, this review provides a comprehensive and up-to-date assessment of the evidence,” said Dr. Rochelle Walensky, the Vaccine Integrity Project’s Medical Advisor and professor of medicine at Harvard Medical School. “The data show that Tdap vaccination during pregnancy is an effective way to protect infants from a serious disease at a time when they are most at risk. The safety profile remains consistently strong across a large body of research, giving prospective parents confidence that they can safely protect their newborns from a serious disease that infected tens of thousands of people last year.”
The authors note that some limitations remain in the evidence base, particularly in measuring rare outcomes and increased risk of bias in studies of large, observational datasets. However, these limitations do not change the overall conclusion that Tdap vaccination during pregnancy is both safe and beneficial.
Overall, the review concludes that maternal Tdap vaccination provides clear public health benefits, reducing the risk of pertussis and its complications in early infancy while maintaining a strong safety profile. The findings support current recommendations for vaccination during each pregnancy and underscore the importance of continued monitoring and research.
Media Contact:
Kevin Griffis
Director of Media Relations and Public Affairs
Center for Infectious Disease Research and Policy
University of Minnesota
kgriffis@umn.edu
202-412-8377