Ruminations: COVID Vaccinations During Pregnancy -- No Side Effects

"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."
"The results of this study provide further evidence for care providers and pregnant people about the safety of COVID-19 vaccination during pregnancy."
Dr. Deshayne Fell, scientist, CHEO Research Institute, associate professor of medicine, University of Ottawa

MothertoBaby

A new retrospective study led by the CHEO Research Institute examined thousands of births in Ontario, concluding that being vaccinated against COVID-19 while pregnant does not have the effect of increasing risk of complications, such as giving birth early or having a small or stillborn baby. Their findings were published in The BMJ (British Medical Journal).

Starting with the acknowledgement that acquiring the virus while pregnant links to a higher risk of complications that include admission to hospital, maternal death and both preterm birth and stillbirth, the researchers were interested in settling the conviction that vaccination against COVID during pregnancy truly has demonstrated benefits helping protect mothers and their babies. Limited evidence linking pregnancy outcomes after vaccination drew them to this study.

The CHEO-based BORN Ontario birth registry was used by the researchers to identify infants born following at least 20 weeks or pregnancy or weighing at least 500 g between May 1 and December 31, 2021. The data gleaned was then linked to CO-VaxON, the immunization database of Ontario's COVID-19 program.

It was found that of 85,162 births, 43,099 represented people who received at least one dose of COVID-19 vaccine during pregnancy; 99.7 percent having received an mRNA vaccine, mostly those produced by Pfizer-BioNTech, or Moderna. The study led to the discovery that vaccination during pregnancy was not associated with increased risk of overall preterm birth which was experienced by 6.5 percent of those unvaccinated; spontaneous preterm birth, at 3.7 percent versus 4.4 percent; or very preterm birth, at 0.59 percent versus 0.89 percent.

Findings, reported the researchers, were similar irrespective of when the vaccine was given, how many doses were received during pregnancy, or which mRNA vaccine was used. Extenuating factors such as 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, were all accounted for.

No increase was found in the risk of babies being born small for gestational age, at 9.1 percent in the vaccinated group as opposed to 9.2 percent among the unvaccinated, or stillbirth, at 0.25 percent opposed to 0.44 percent. Research findings were similar irrespective of when the vaccine was given, how many doses were received during pregnancy, or which mRNA vaccine was used.

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 were all taken into account.

A different study, also co-authored by Dr.Fell, showed 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 throughout the first four months of life. That research was published in June, in JAMA Internal Medicine.