New evidence confirms COVID-19 vaccination in pregnancy is safe for babies
The largest study to date suggests that receiving an mRNA-based COVID-19 vaccine in pregnancy may be associated with fewer general complications during birth.
- 6 February 2024
- 3 min read
- by Linda Geddes
Babies whose mothers receive a COVID-19 vaccine during pregnancy are at no greater risk of adverse events and may be at lower risk of severe complications during birth, new data suggests.
The study – the largest to assess the impact of COVID-19 vaccination in pregnancy to date – provides reassurance that maternal vaccination is safe for developing infants.
Babies born to vaccinated individuals had half the risk of death of those whose mothers had not been vaccinated.
COVID-19 vaccination is strongly recommended during pregnancy because it reduces the risk of infection for mother and baby. Even so, concerns about potential adverse events have resulted in fewer pregnant women taking up the offer of vaccination compared to other individuals of the same age.
To investigate the impact of COVID-19 vaccination in pregnancy on developing infants, Mikael Norman, a professor of paediatrics and neonatology the Karolinska Institute in Stockholm, Sweden, and colleagues turned to national registers in Norway and Sweden containing data from 98% of newborns conceived after COVID-19 vaccines became available.
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Of the 196,470 infants included in the study, 52% of their mothers were not vaccinated against COVID-19, while the remaining 48% had received one or more doses of an mRNA-based COVID-19 vaccine – either the Pfizer/BioNtech or Moderna vaccine. The babies' health was followed for at least four weeks after they were born.
The study, published in JAMA, found that COVID-19 vaccination in pregnancy was not associated with any increased risks in newborn infants. On the contrary, babies born to vaccinated individuals had half the risk of death of those whose mothers had not been vaccinated (0.9 vs. 1.8 deaths per 1,000 births). They were also at significantly lower risk of brain bleeds (1.7 vs. 3.2 per 1,000 births) and a type of brain damage caused by reduced oxygen supply to the brain before or shortly after birth (1.8 vs. 2.7 per 1,000 births). The incidence of other types of bleeding, blood clots or inflammation in various organ systems did not differ between the groups.
“COVID-19 is still present in society and is probably something we will have to deal with for a long time. It is therefore very important for the 100,000 women who become pregnant every year in Sweden, and the 130 million in the world, to know that vaccination with mRNA-vaccines against COVID-19 is safe for their babies."
– Mikael Norman, professor of paediatrics and neonatology, Karolinska Institute, Sweden
The researchers are unsure why babies born to mothers who received a COVID-19 vaccine were at lower risk of these complications, but they believe a direct vaccine effect is unlikely. "Previous studies have shown that the vaccine does not cross the placenta and that it cannot be found in umbilical cord blood," Norman said.
Although COVID-19 is no longer categorised as a Public Health Emergency of International Concern, it remains a global health threat. "COVID-19 is still present in society and is probably something we will have to deal with for a long time," said Norman. "It is therefore very important for the 100,000 women who become pregnant every year in Sweden, and the 130 million in the world, to know that vaccination with mRNA-vaccines against COVID-19 is safe for their babies. We found no increased risks, if anything, infants to vaccinated women had lower risks for some severe outcomes."