A recent study published in the JAMA Network examined the potential link between the administration of the COVID-19 mRNA vaccine in pregnant women and adverse events in their newborns. The researchers utilized an extensive sample cohort of 94,303 cases and 102,167 controls and found that mRNA vaccines are not only not associated with adverse outcomes, but that they also reduce the odds ratios (ORs) of neonatal cerebral ischemia and hypoxic-ischemic encephalopathy, intracranial bleeding, and mortality. These findings support the vaccination efforts and recommendations of various authorities for vaccination during pregnancy.
Why Do Pregnant Women Need COVID-19 Vaccines?
The COVID-19 pandemic is one of the most socioeconomically, medically, and infrastructurally devastating global diseases in recent history. Since its discovery in Wuhan, China, at the end of 2019, the pandemic has infected over 700 million people and claimed almost 7 million lives. Fortunately, global vaccination efforts have made great strides in containing the spread of the virus and preventing new outbreaks. Mono- and polyvalent messenger RNA (mRNA) vaccines have proven particularly effective in controlling the spread of the disease.
Studies to elucidate the effects of COVID-19 vaccinations during pregnancy have shown that vaccination is an effective form of anti-COVID-19 vaccination for both mothers and their unborn/newborn infants, prompting various global authorities to recommend their use. Unfortunately, the existing literature evaluating vaccine safety in this diverse group has utilized limited sample sizes, limiting their analytical power and giving vaccine opponents cause for debate despite their generally positive results.
Unverified reports of potential brain lesions in newborns have prompted authorities and even doctors to express concerns about the need for vaccination during pregnancy. Clarifying the benefits of vaccinations during pregnancy and demonstrating their safety in a large cohort case-control study would silence the criticism and could lead to useful anti-COVID-19 interventions in the future.
About the Study
In the present study, researchers conducted a comprehensive assessment of neonatal safety after mRNA vaccine administration in order to address the concerns expressed by authorities, physicians, and vaccine opponents regarding the necessity of vaccinations during pregnancy. Given the recurring claim of vaccine-related brain lesions in newborns, this study focused on elucidating cerebrovascular outcomes in newborns.
The study sample cohort was derived from a population-based cohort study conducted in Norway and Sweden, which included all live births at 22 weeks or more, including newborns with congenital disabilities as per the definition of the European network of population-based registries for the epidemiological surveillance of congenital anomalies. As this work focused on the safety of mRNA vaccines, vaccine data for other vaccine types were omitted from the analyses. The application of exclusion criteria still encompassed 97.4% and 98.6% of all live births in Sweden and Norway, respectively.
The study lasted from January 2021 to January 2023 and included 94,303 (vaccinated) cases and 102,167 (unvaccinated) controls. Demographic data (nationality, education level, cohabitation with partner, age, parity, smoking status, and body mass index [BMI]) and medical information (pregnancy comorbidities, conception season, gestational diabetes, multiple or singleton pregnancy, mode of delivery, and COVID-19 infection status) were collected from eight different national registers using unique personal identity numbers. Vaccine data included the number of received mRNA vaccine doses (before and during pregnancy), vaccine manufacturer, time from last vaccination to birth (days), and time from conception to last vaccination (days).
„Exposure was defined as vaccination with an mRNA COVID-19 vaccine during pregnancy, regardless of prior mRNA vaccination, number of doses during pregnancy, or vaccine manufacturer. Vaccination during pregnancy was defined as vaccination at any time between conception and delivery. The recommended vaccines for pregnant women were the two mRNA vaccines from Pfizer-BioNTech (BNT162b2) and Moderna (mRNA-1273).“
All outcomes were defined and measured based on the codes of the 10th Revision of the International Statistical Classification of Diseases and Related Health Problems. Associations were estimated using multivariable analyses adjusted for covariates. Odds ratios (ORs) were calculated using logistic regression. Data from Sweden and Norway were initially analyzed independently, then combined and re-analyzed.
Study Results and Conclusions
No negative effects of vaccination on the newborn were identified. On the contrary, the likelihood of infants born to mothers who received mRNA COVID-19 vaccines during pregnancy being born premature, having a low Apgar score, or being small for gestational age (SGA) was less frequent. Encouragingly, vaccination was also associated with lower ORs for non-traumatic intracranial bleeding in newborns and neonatal mortality. If the vaccine was received during the second trimester, the risks of cerebral ischemia and hypoxic-ischemic encephalopathy were further reduced.
„This large population-based safety study found no evidence of an increase in adverse events in infants born to individuals vaccinated against COVID-19 during pregnancy. On the contrary, exposure to COVID-19 vaccination during pregnancy was associated with a lower rate of non-traumatic intracranial bleeding, hypoxic-ischemic encephalopathy, and neonatal mortality.“
These findings can help silence vaccine opponents and alleviate the concerns of authorities and physicians that COVID-19 mRNA vaccines are both safe and beneficial for use during pregnancy. While close monitoring of vaccinated mothers must be conducted, these results pave the way for renewed vaccination efforts that could lead to further progress in containing the pandemic.