FULL CLAIM: COVID-19 vaccines increase the risk of miscarriages and stillbirths
Vaccine misinformation founded on misleading presentations of data from adverse event databases are still going strong on social media. One example of this is a graph posted by Instagram users in March 2023, depicting a sharp increase in miscarriages and stillbirths reported to the U.S. Vaccine Adverse Events Reporting System (VAERS).
Included in the post is the hashtag #FauciForPrison, referencing the former director of the U.S. National Institute of Allergy and Infectious Diseases (NIAID) and chief medical advisor to the U.S. President during the COVID-19 pandemic.Together, these elements implied that COVID-19 vaccines were to blame for the uptick in miscarriages and stillbirths reports.
However, such claims are inaccurate and contradicted by scientific evidence, misusing VAERS data in a way that promotes vaccine misinformation. This review explains why.
Scientific data indicates that COVID-19 vaccines are safe for pregnant women
The initial clinical trials undertaken for the COVID-19 vaccines’ authorization excluded pregnant women due to ethical and legal concerns. This is common practice for new drugs and vaccines but does lead to a lack of data on that population. However, this information gap has since been filled by later studies and there is now a wealth of data showing that pregnancy outcomes are similar between vaccinated and unvaccinated women.
In a retrospective study on more than 85,000 births in Canada, researchers found that COVID-19 vaccination didn’t increase the risks of negative pregnancy outcomes such as stillbirths, preterm birth or small for gestational age at birth.
Another study on women who gave birth between March 2020 and July 2021 in England found no differences in the risk of stillbirths and other perinatal safety outcomes, such as fetal abnormalities or small for gestational age.
Another study analyzed the risk of miscarriage or ectopic pregnancy of vaccinated women compared to unvaccinated women and to pre-pandemic historical data. They found that the COVID-19 vaccination wasn’t associated with any increased risks of miscarriage and ectopic pregnancy. A study from Switzerland comparing the rate of pregnancy negative-outcome in vaccinated women to pre-pandemic historical data reached similar conclusions.
Other studies took the reverse approach. Instead of comparing how many women had a miscarriage between the vaccinated and unvaccinated categories, they compared how many women were recently vaccinated between the “miscarriage” and the “ongoing pregnancy” categories. Consistent with all the results above, they didn’t find any overrepresentation of vaccinated women in the category who suffered a miscarriage. In other words, there was no association between vaccination and miscarriage[6,7].
Systematic reviews of the available scientific literature on the topic also found that COVID-19 vaccination didn’t raise the risks for miscarriages or stillbirths[8,9].
Not only COVID-19 wasn’t associated with a risk of pregnancy loss, but it didn’t increase the risk for other pregnancy negative outcomes either. Indeed, studies from the U.S. and Israel found that vaccinated and unvaccinated women had equal risks of outcomes like preterm births or small for gestational age[10,11].
In conclusion, all these studies consistently showed that COVID-19 vaccines don’t cause miscarriages or stillbirths.
Pharmacosurveillance databases like VAERS alone cannot establish that a vaccine caused the adverse event
Using VAERS data showing an increase of miscarriages in 2021 and 2022 to imply that COVID-19 vaccines are dangerous is misleading and is a misuse of the database. VAERS provides the general public and healthcare workers with an avenue to report adverse events occurring in people after they were vaccinated. The system is co-managed by the U.S. Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA). It serves as “a national early warning system to detect possible safety problems in U.S.-licensed vaccines”, which “can provide CDC and FDA with valuable information that additional work and evaluation is necessary to further assess a possible safety concern.”
However, the database alone cannot be used to suggest that a vaccine is dangerous, as Health Feedback explained in previous reviews. First, because anyone can submit a report to VAERS, the information in the report isn’t verified. VAERS clearly warns users relying on the database about this caveat: “Some reports may contain information that is incomplete, inaccurate, coincidental, or unverifiable. Most reports to VAERS are voluntary, which means they are subject to biases”.
Second, VAERS data alone can’t show whether an adverse event is the consequence of vaccination. Indeed, the sole fact that event A occurs before event B doesn’t mean that the first one caused the second. Suggesting otherwise is known as the post hoc ergo propter hoc fallacy. Further investigation into VAERS reports are required in order to determine whether there is a causal association.
Lastly, the number of adverse events such as deaths or miscarriages reported into VAERS is influenced by people’s propensity to file such reports. The intense media attention on COVID-19 vaccines and their safety has likely produced a greater level of public awareness, which plausibly also led to more reports being submitted, as biostatistician Jeffrey Morris told FactCheck.org. Therefore, the larger number of reports being submitted for the COVID-19 vaccines compared to previous vaccines isn’t necessarily a sign of a more dangerous vaccine.
- 1 – Smith et al. (2020) Exclusion of Pregnant Women from Clinical Trials during the Coronavirus Disease 2019 Pandemic: A Review of International Registries. American Journal of Perinatology.
- 2 – Fell et al. (2022) Risk of preterm birth, small for gestational age at birth, and stillbirth after covid-19 vaccination during pregnancy: population based retrospective cohort study. The British Medical Journal.
- 3 – Blakeway et al. (2021) COVID-19 vaccination during pregnancy: coverage and safety. American Journal of Obstetrics and Gynecology.
- 4 – Calvert et al. (2022) A population-based matched cohort study of early pregnancy outcomes following COVID-19 vaccination and SARS-CoV-2 infection. Nature communications.
- 5 – Favre et al. (2022) COVID-19 mRNA vaccine in pregnancy: Results of the Swiss COVI-PREG registry, an observational prospective cohort study. The Lancet Regional Health Europe.
- 6 – Magnus et al. (2021) Covid-19 Vaccination during Pregnancy and First-Trimester Miscarriage. The New England Journal of Medicine.
- 7 – Kharbanda et al. (2021) Spontaneous Abortion Following COVID-19 Vaccination During Pregnancy. Journal of the American Medical Association.
- 8 – Fu et al. (2021) Systematic review of the safety, immunogenicity, and effectiveness of COVID-19 vaccines in pregnant and lactating individuals and their infants. International Journal of Gynecology and Obstetrics.
- 9 – Rimmer et al. (2023) The risk of miscarriage following COVID-19 vaccination: a systematic review and meta-analysis. Human Reproduction.
- 10 – Lipkind et al. (2022) Receipt of COVID-19 Vaccine During Pregnancy and Preterm or Small-for-Gestational-Age at Birth — Eight Integrated Health Care Organizations, United States, December 15, 2020–July 22, 2021. Morbidity and Mortality Weekly Report.
- 11 – Wainstock et al. (2021) Prenatal maternal COVID-19 vaccination and pregnancy outcomes. Vaccine.