COVID vaccine during pregnancy not linked to adverse outcomes

Pregnant women who received a COVID-19 vaccine were at no additional risk of adverse birth outcomes compared to those who had not been vaccinated, according to a retrospective cohort study.

COVID-19 vaccination during pregnancy has not been associated with an increased risk of preterm labor (adjusted risk ratio [aHR] 0.91, 95% CI 0.82-1.01) or small for gestational age (GAS) at birth (aHR 0.95, 95% CI 0.87-1.03), reported Heather Lipkind, MD, MS, of Yale University in New Haven, Connecticut, and colleagues from Weekly Mortality and Morbidity Report.

However, only 21.8% of the more than 40,000 pregnant women in the study were vaccinated, the researchers noted.

Lipkind and colleagues added that although the absolute risk of severe morbidity associated with COVID-19 during pregnancy is low, pregnant women with symptomatic illness have an increased risk of intensive care admission, invasive ventilation, resuscitation. and even deaths compared to non-pregnant women with COVID-19[FEMININEDeplusleschercheursrecueillentplusdepreuvessurlesavantagesdelavaccinationCOVID-19pendantlagrossessecommelaprésenced’anticorpsdanslesangdecordon

“Together, these findings reinforce the importance of communicating the risks of COVID-19 during pregnancy, the benefits of vaccination, and information on the safety and effectiveness of COVID-19 vaccination during pregnancy,” said said Lipkind’s group.

The CDC recommends COVID-19 vaccination during pregnancy and further suggests that all adults – including those who are pregnant, breastfeeding, or trying to become pregnant – be given a booster. The American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine recommend vaccination against COVID-19 during pregnancy.

Lipkind and her colleagues analyzed 46,079 single pregnancies from December 2020 to July 2021, obtaining data from eight health centers as part of the CDC Vaccine Safety Datalink (VSD) project. They included women aged 16 to 49, who were due to give birth between February and July 2021.

In the vaccinated group (n = 10,064), the mean age was 32.2 years, 43% were non-Hispanic Caucasian, 25.6% were Asian, and 24.5% were Hispanic. The mean age in the unvaccinated group (n = 36,015) was 29.8 years, while 38.4% were Hispanic, 32.2% were white, and 15.7% were Asian. Obesity, defined as a BMI 30 before pregnancy or in the first trimester, was the most common comorbidity in the two groups.

The authors collected data from standardized VSD files, electronic health records, insurance claims, and national or local immunization databases to identify those who received a COVID vaccine during pregnancy. Doses of vaccine that were given from a woman’s last menstrual period up to 3 days before childbirth were included.

Lipkind’s group then compared the rates of preterm infants and PSG at birth (defined as birth weight below the 10th percentile for gestational age) between the vaccinated and unvaccinated groups, performing separate analyzes based on the number of doses received and quarter of administration.

Almost everyone who was vaccinated received their injection in the second (37%) or third trimester (62%).

Most of those vaccinated received an mRNA vaccine – 54% Pfizer / BioNTech, 41% Moderna – and 4% received the Johnson & Johnson vaccine. Of those who received an mRNA vaccine, 82% received both doses.

The overall prevalence of preterm births and PSGs at birth was 6.6 and 8.2 per 100 live births, respectively. Vaccination against COVID-19 was not associated with an increased risk of either outcome, and no association was seen when analyzed by mRNA vaccine dose or quarterly vaccination, the researchers found.

The limitations of the study included the fact that it may not have captured all vaccinations during pregnancy, potentially skewing the results towards zero. Additionally, the authors were unable to account for some confounding factors, including a history of prematurity or PSG at birth and a previous infection with COVID-19 that may have affected the vaccination. The researchers added that very few study participants were vaccinated during the first trimester and that future studies should explore the safety of vaccination during this time.

  • Amanda D’Ambrosio is a reporter on the MedPage Today Corporate and Investigative Team. She covers obstetrics and gynecology and other clinical news, and writes articles on the US healthcare system. To follow


Lipkind and his co-authors disclosed relationships with Pfizer, Johnson & Johnson, NIH, and the National Institute of Allergy and Infectious Diseases.

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