No increase in pregnancy problems following COVID-19 immunisation

Vaccination against COVID-19 during pregnancy is not related with an increased risk of pregnancy problems, according to a large-scale registry research published in the journal JAMA by Karolinska Institutet in Sweden and the Norwegian Institute of Public Health.

The research, which included over 160,000 pregnancies, discovered no increase in the risk of preterm delivery, growth retardation, low Apgar scores at birth, or the requirement for neonatal care following COVID-19 immunisation during pregnancy.

“The results are comforting, and perhaps will make pregnant women more inclined to be vaccinated,” says co-first author Anne rtqvist Rosin, a researcher at Karolinska Institutet’s Department of Medicine (Solna).

Previous research has revealed that pregnant women are at a greater risk of dying from severe COVID-19 infections that require intensive care than non-pregnant women of reproductive age. Pregnant women who have severe COVID-19 are also more likely to give birth prematurely.

Efficacious COVID-19 vaccinations have been available in Sweden and Norway since January 2021, and Sweden advised a COVID-19 shot for all pregnant women in May 2021, followed by Norway in August.
“We’re still seeing lower vaccination rates than in the general population, so there’s probably some worry about how the immunizations effect the pregnant individual and the foetus,” adds Dr. rtqvist Rosin.

The researchers linked Sweden’s Pregnancy Registration and Norway’s Medical Birth Register to each country’s vaccination register to get information on whether and when pregnant women were vaccinated, as well as which vaccine they received. The study comprised 157,521 women who gave birth between January 2021 and January 2022, with nearly one-fifth (18%) of them having been vaccinated. It was discovered that vaccinated people were no more likely than unvaccinated people to experience one of the problems evaluated.

According to current recommendations, the majority of the pregnant women in the research were vaccinated after week 12. A mRNA vaccination was given to 95% of the participants (Pfizer-BioNTech or Moderna). This should be considered when evaluating the results, which were identical for the various mRNA vaccinations regardless of whether one or two doses were administered. Vaccination throughout the third trimester, as well as vaccination with the Moderna vaccine, was linked to a decreased risk of neonatal care.

One possible benefit of immunisation during pregnancy is that the antibodies produced travel through the placenta, providing the newborn infant with some protection against COVID-19.

“We’re now aiming to examine how long this protection lasts, and if SARS-CoV-2 infection or vaccination during pregnancy has any further long-term impacts on the child’s health,” adds co-last author Professor Olof Stephansson of Karolinska Institutet’s Department of Medicine (Solna).

Researchers from Sweden’s Karolinska Institutet and Norway’s Norwegian Institute of Public Health collaborated on the study. It was funded by the Norwegian Research Council, NordForsk, and the European Research Council (ERC). Rickard Ljung, co-author and KI researcher, has received a remuneration from Pfizer outside of the scope of this study and works for the Swedish Medical Products Agency. There have been no reports of additional possible conflicts of interest.