COVID-19 mRNA vaccine given in third-trimester pregnancy is not associated with adverse maternal outcomes

Reference

Rottenstreich M, Sela HY, Rotem R, Kadish E, Wiener-Well Y, Grisaru-Granovsky S. Covid-19 vaccination during the third trimester of pregnancy: rate of vaccination and maternal and neonatal outcomes, a multicentre retrospective study. BJOG 2022;129(2):48-55.

Synopsis

This retrospective cohort study compared birth outcomes among women who were vaccinated with the Pfizer-BioNTech mRNA COVID-19 vaccine during the third trimester of pregnancy and those who were not vaccinated. Included women were 18 years or older and delivering at either of 2 hospitals in Jerusalem, Israel, under their National Health Plan between January 19, 2021, and April 27, 2021. Women were excluded if they had documentation of a positive SARS-CoV-2 polymerase chain reaction test result during pregnancy or delivery, had only one vaccine dose, or had undocumented vaccination or testing status. Among the 1775 total women included in the study, 712 (40.2%) were vaccinated. Vaccinated women were, on average, approximately 1 year older and were more likely to have had a prior cesarean delivery. The primary outcome was a composite adverse maternal outcome rate, which included one or more of the following: chorioamnionitis, postpartum hemorrhage, endometritis, blood transfusion, cesarean delivery, intensive care unit admission, or prolonged hospital stay, (> 5 days for vaginal delivery or > 7 days for cesarean birth). Vaccinated women did not differ from unvaccinated women for the primary outcome (adjusted odds ratio [aOR] 0.8; 95% CI 0.61 - 1.03). The secondary outcome was an adverse neonatal outcome rate, which included one or more of the following: intrauterine fetal death, Apgar score of 7 or less at 1 minute, Apgar score of 7 or less at 5 minutes, admission to the neonatal intensive care unit, neonatal asphyxia, intracranial hemorrhage, meconium aspiration syndrome, hyperbilirubinemia, neonatal seizures, neonatal hypoglycemia, neonatal sepsis, or the use of mechanical ventilation. The secondary composite outcome favored the vaccinated group (aOR 0.5; 0.36 - 0.74). Because of the observational nature of the study, causal inference of benefit must be constrained.