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home / 世界杯决赛2022

cheo research institute study finds no link between covid-19 vaccination in pregnancy and preterm birth, stillbirth

'the results of this study provide further evidence for care providers and pregnant people about the safety of covid-19 vaccination during pregnancy.'

by megan gillis
published aug 29, 2022
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getting vaccinated against covid-19 while pregnant doesn’t increase the risk of complications like giving birth early or having a small or stillborn baby, according to a new retrospective study led by the cheo research institute that looked at thousands of births in ontario. “our study found no evidence of increased risk of preterm birth, very preterm birth, small-for-gestational-age at birth, or stillbirth following covid-19 vaccination during pregnancy,” lead author dr. deshayne fell, a scientist at the cheo research institute and an associate professor of medicine at the university of ottawa, said in a news release.
“the results of this study provide further evidence for care providers and pregnant people about the safety of covid-19 vaccination during pregnancy.”
the findings were published aug. 17 in the bmj.
researchers knew that getting the virus while pregnant was linked to a higher risk of complications including being admitted to hospital, maternal death, and both preterm birth and stillbirth. but while getting vaccinated during pregnancy has been shown to help protect mothers and their babies, there was limited evidence about pregnancy outcomes after vaccination.
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researchers used the cheo-based born ontario birth registry to identify infants born after at least 20 weeks of pregnancy or weighing at least 500g between may 1 and dec. 31, 2021. the information was then linked to covaxon, ontario’s covid-19 immunization database.
of 85,162 births, 43,099 were to people who received at least one dose of a covid-19 vaccine during pregnancy, 99.7 per cent  of them an mrna vaccine, mainly those made by pfizer-biontech or moderna.
vaccination during pregnancy was not associated with an increased risk of overall preterm birth, experienced by 6.5 per cent of those vaccinated and 6.9 per cent of those unvaccinated, spontaneous preterm birth, at 3.7 per cent versus 4.4 per cent, or very preterm birth, at 0.59 per cent versus 0.89 per cent.
nor was an increase found in the risk of babies being born small for gestational age, at 9.1 per cent in the vaccinated group versus 9.2 per cent among those unvaccinated, or stillbirth, at 0.25 per cent versus 0.44 per cent.
the researchers reported that findings were similar regardless of when the vaccine was given, how many doses were received during pregnancy or which mrna vaccine was given.
the study took into account factors including the mother’s age at delivery, pre-pregnancy body mass index, reported smoking or substance use during pregnancy, pre-existing health conditions, previous live births and stillbirths, location and income.
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the project was supported by the public health agency of canada through the vaccine surveillance reference group and the covid-19 immunity task force.
researchers say there are still some important questions that merit future study, including assessing vaccination before pregnancy or around conception and non-mrna vaccines during pregnancy.
another study co-authored by fell showed that infants whose mothers received a second or third dose of covid-19 vaccine during the late stages of pregnancy were protected against sars-cov-2 infection during the first four months of life. the research was published in jama internal medicine in june.

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