COVID vaccination during pregnancy is not associated with a higher risk of pregnancy complications, according to a large scale Swedish and Norwegian study published in the journal JAMA.
The study, which comprised almost 160 000 pregnancies, found there to be no increase in the risk of preterm birth, growth retardation, low Apgar scores at birth or the need for neonatal care after vaccination against COVID during pregnancy.
“The results are reassuring and can hopefully make pregnant individuals more willing to get vaccinated,” said co-first author Anne Örtqvist Rosin, researcher at the Department of Medicine, Karolinska Institutet.
Studies have shown that, compared to non-pregnant peers, pregnant women are at risk of serious COVID requiring intensive care with a higher risk of death. Preterm births are also more likely in pregnant women with severe COVID. COVID vaccines have been available in Sweden and Norway since January 2021, and in May 2021 Sweden recommended all pregnant individuals to have a COVID jab, followed in August by Norway.
“We’re still seeing that vaccination rates are lower than in the rest of the population, so it’s likely that there’s some concern about how the vaccines affect the pregnant individual and the foetus,” explained Dr Örtqvist Rosin. “When the vaccines were produced, pregnant women were not included in the large clinical studies, and until now there have been no population-based data about any risk there might be to them.”
The researchers linked Sweden’s Pregnancy Register and Norway’s Medical Birth Register to each country’s vaccination register to obtain data on if and when pregnant individuals were vaccinated and with which vaccine. The study included a total of 157 521 individuals who gave birth between January 2021 and January 2022, of whom 18% had been vaccinated. It was found that vaccinated individuals were at no higher risk than unvaccinated of developing one of the studied complications.
The majority of the pregnant individuals included in the study were vaccinated after week 12 in accordance with current recommendations, and 95% received an mRNA vaccine. This should be factored in when interpreting the results, which were similar for the different mRNA vaccines regardless of whether one or two doses were given. Vaccination during the third trimester and vaccination with the Moderna vaccine was associated with a slightly lower risk of needing neonatal care.
A possible benefit of vaccination during pregnancy is that the antibodies generated pass through the placenta, conferring a certain degree of protection against COVID to the newborn baby.
“We’re now planning to study how long this protection lasts, and if SARS-CoV-2 infection or vaccination during pregnancy has any other lasting effects on the child’s health,” said joint last author Professor Olof Stephansson at the Karolinska Institutet .
Source: Karolinska Institutet
