Large Study Shows No Increased Risk from COVID-19 Shots in Pregnant Women

Pregnant women are at higher risk of having severe COVID-19, which also could endanger their unborn child. But, worldwide, misinformation campaigns appear to have kept vaccination rates too low. Find out how a new Scandinavian study determined no increase in the risks of preterm birth, growth retardation, low Apgar scores or the need for neonatal care in expectant mothers who get COVID-19 vaccines or their babies.

OSLO, NORWAY – Vaccination against COVID-19 during pregnancy does not create a higher risk of pregnancy complications, according to a large-scale Scandinavian registry study.

Researchers from Karolinska Institutet in Sweden and the Norwegian Institute of Public Health focused on vaccination against SARS-C0V-2 in nearly 160,000 pregnancies and identified no increase in the risk of preterm birth, growth retardation, low Apgar scores at birth or the need for neonatal care.

 "The results are reassuring and can hopefully make pregnant individuals more willing to get vaccinated," said co-first author Anne Örtqvist Rosin, MD, PhD, a researcher at the Department of Medicine, Karolinska Institutet (Solna).

The information is especially important because earlier studies have shown – and the U.S. Centers for Disease Control and Prevention has warned -- that pregnant women are at risk for more serious COVID-19 requiring intensive care with a higher risk of death than non-pregnant women of fertile age. Evidence also indicates that pregnant women with severe COVID-19 are more likely to have preterm births.

Despite recommendations that all pregnant women be vaccinated in Sweden in Norway in 2021, the rates have lagged.

"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 fetus," Örtqvist Rosin noted. "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."

For the population-based retrospective cohort study published in JAMA, researchers focused on 157 521 deliveries in Sweden and Norway. They determined that SARS-CoV-2 vaccination during pregnancy, compared with no SARS-CoV-2 vaccination during pregnancy, was not significantly associated with risk of preterm birth (adjusted hazard ratio [aHR], 0.98), stillbirth (aHR, 0.86), small for gestational age (adjusted odds ratio [aOR], 0.97), low Apgar score (aOR, 0.97), or neonatal care admission (aOR, 0.97).

The pregnant women received either mRNA vaccines—BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna)—or a viral vector vaccine—AZD1222 (AstraZeneca.

Among the 157,521 singleton births included in the study – 103,409 in Sweden and 54, 112 in Norway --the mean maternal age at the time of delivery was 31 years, according to the authors. They advise that 18% were vaccinated against SARS-CoV-2 -- 12.9% with BNT162b2, 4.8% with mRNA-1273, and 0.3% with AZD1222-- while pregnant. Most, 8.3% and 9.1%, respectively, were vaccinated during the second and third trimesters with only 0.7% receiving shots in the first trimester, according to the study.

“In this population-based study conducted in Sweden and Norway, vaccination against SARS-CoV-2 during pregnancy, compared with no SARS-CoV-2 vaccination during pregnancy, was not significantly associated with an increased risk of adverse pregnancy outcomes,” researchers concluded. “The majority of the vaccinations were with mRNA vaccines during the second and third trimesters of pregnancy, which should be considered in interpreting the findings.”

A potential advantage of vaccination during pregnancy is that the antibodies can pass through the placenta and protect the newborn baby, according to the authors.

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