No link between COVID-19 in pregnancy and higher risk of preterm birth or stillbirth

Covid-19 infection during pregnancy has been associated with higher risks of complications, including admission to hospital and death for pregnant individuals, as well as preterm birth and stillbirth.Covid-19 vaccination during pregnancy has been shown to be effective against covid-19 in pregnant individuals as well as their newborns, but evidence about pregnancy outcomes after covid-19 vaccination during pregnancy from large studies is limited.

To address this, researchers set out to assess the risk of preterm birth, small for gestational age at birth, and stillbirth after covid-19 vaccination during pregnancy. They used a population-based birth registry to identify all liveborn and stillborn infants with a gestational age of at least 20 weeks or birth weight of at least 500g in Ontario, Canada between 1 May and 31 December 2021.This information was then linked to the database that captures all covid-19 immunisations in the province.

Of 85,162 births, 43,099 occurred in individuals who received one dose or more of a covid-19 vaccine during pregnancy - 42, 979 (99.7%) received an mRNA vaccine, mainly Pfizer-BioNTech or Moderna.

The researchers found that vaccination during pregnancy was not associated with any increased risk of overall preterm birth (6.5% among vaccinated v 6.9% among unvaccinated), spontaneous preterm birth (3.7% v 4.4%), or very preterm birth (0.59% v 0.89%).No increase was found in risk of small for gestational age at birth or stillbirth. Findings were similar irrespective of what stage (trimester) of pregnancy vaccination was given, number of doses received during pregnancy, or which mRNA vaccine product.

Ref:

Deshayne B Fell et. al,Risk of preterm birth, small for gestational age at birth, and stillbirth after covid-19 vaccination during pregnancy: population based retrospective cohort study,The BMJ,10.1136/bmj-2022-071416