evidence: Pregnant women have an increased risk of severe COVID-19 compared with their nonpregnant counterparts and COVID-19 during pregnancy has been associated with fetal and neonatal morbidity and mortality.1,2 Vaccination is routinely recommended to protect pregnant women and their newborns from acute respiratory tract infections, such as influenza and pertussis, and pregnant women are designated a priority group for COVID-19 vaccination in multiple countries.3 Observational studies have demonstrated that the immunogenicity and effectiveness of COVID-19 vaccines are similar in pregnant and nonpregnant populations.4,5 Moreover, COVID-19 vaccination during pregnancy confers protection to infants during the first months of life.6,7 Increased rates of adverse pregnancy or perinatal outcomes, including spontaneous abortion, stillbirth, and preterm birth, following mRNA COVID-19 vaccination during pregnancy have not been observed in epidemiological studies.8-10 [...] By contrast, we found that maternal COVID-19 vaccination during pregnancy was associated with a slightly increased risk of neonatal readmission in unadjusted analyses. We hypothesize the observed increase was due to depletion of susceptibles39; this is supported by the finding that a small proportion of infants in the unexposed group were more likely to be excluded from analyses of readmission either because they died during the birth admission or because their birth admission was longer than 28 days. In the weighted primary analysis and most subgroup/sensitivity analyses, the association between maternal vaccination and neonatal readmission was no longer significant and there was no increase in hospital readmission up to age 6 months.