Maternal COVID-19 Vaccination During Pregnancy Linked to Improved Newborn Outcomes

A recent population-based retrospective cohort study conducted in Ontario, Canada, has yielded encouraging results regarding the impact of maternal messenger RNA (mRNA) COVID-19 vaccination during pregnancy on newborn and early infant health. The study found valuable insights like maternal mRNA COVID-19 vaccination during pregnancy was associated with lower risks of Severe neonatal morbidity, neonatal death, and NICU admission.

The study results were published in the journal JAMA Pediatrics. 

Pregnant women face higher risks from COVID-19. While vaccination is recommended and safe during pregnancy, uptake is lower among certain groups.  Hence, to address the knowledge gap researchers conducted a population-based cohort study to explore how the maternal COVID-19 vaccination affects newborn and early infant outcomes, aiming to boost vaccine confidence.

The research, which used multiple linked health administrative databases, focused on singleton live births with expected delivery dates falling between May 1, 2021, and September 2, 2022. The study period extended from January 2023 through March 2023, allowing for a comprehensive assessment of outcomes related to maternal COVID-19 vaccination during pregnancy.

The primary objective of this retrospective cohort study was to evaluate the impact of maternal mRNA COVID-19 vaccination on newborn and early infant outcomes. The research aimed to assess the safety of this practice, given the limited comparative epidemiological evidence available. The study evaluated several infant outcomes, including severe neonatal morbidity (SNM), neonatal death, neonatal intensive care unit (NICU) admission, neonatal readmission, and hospital admission up to six months of age. The research team used statistical methods, including weighted risk ratios and weighted Cox proportional hazards regression models, to compare outcomes between infants born to mothers who received COVID-19 vaccination during pregnancy and those born to mothers who did not receive any COVID-19 vaccine doses before delivery.

Study Findings:

• The study included a total of 1,42,006 infants, of which 85,670 were exposed to one or more doses of the COVID-19 vaccine in utero, accounting for 60% of the cohort. 
• Reduced Neonatal Morbidity: Infants born to vaccinated mothers showed a lower risk of severe neonatal morbidity (7.3% in the vaccinated group compared to 8.3% in the unvaccinated group).
• Lower Neonatal Mortality: The study found that neonatal death was less common in infants of vaccinated mothers, with a mortality rate of 0.09% compared to 0.16% in the unvaccinated group.
• Decreased NICU Admissions: Neonatal intensive care unit (NICU) admissions were also less frequent among newborns whose mothers had received the COVID-19 vaccine during pregnancy (11.4% compared to 13.1%).
• The study did not identify any association between maternal vaccination during pregnancy and neonatal readmission or hospital admissions up to 6 months of age.
• Neonatal readmission rates stood at 5.5% for the vaccinated group and 5.1% for the unvaccinated group, while 6-month hospital admissions were reported in 8.4% of the vaccinated group and 8.1% of the unvaccinated group.

The results of this population-based cohort study in Ontario, Canada, offer important insights into the safety and benefits of maternal mRNA COVID-19 vaccination during pregnancy. It demonstrated that such vaccination was associated with lower risks of severe neonatal morbidity, neonatal death, and NICU admission. Importantly, there was no evidence of increased neonatal readmission or hospitalization within the first 6 months of life for infants born to vaccinated mothers.

Further reading: Jorgensen SCJ, Drover SSM, Fell DB, et al. Newborn and Early Infant Outcomes Following Maternal COVID-19 Vaccination During Pregnancy. JAMA Pediatr. Published online October 23, 2023. doi:10.1001/jamapediatrics.2023.4499