What is known about this topic? Pregnant women with COVID-19 are at increased risk of severe illness and adverse birth outcomes, yet many remain reluctant to get vaccinated. What does this report add? In a retrospective cohort of >40,000 pregnant women, COVID-19 vaccination during pregnancy was not associated with preterm birth or small-for-gestational-age birth overall, stratified by trimester of vaccination or number of vaccine doses received during pregnancy, compared to unvaccinated pregnant women. What are the implications for public health practice? These data support the safety of the COVID-19 vaccine during pregnancy. The CDC recommends the COVID-19 vaccine for women who are pregnant, have recently been pregnant, are trying to get pregnant now, or might get pregnant in the future. |
COVID-19 vaccines are recommended during pregnancy to prevent severe maternal morbidity and adverse birth outcomes; however, vaccination coverage among pregnant women has been low. Concerns among pregnant women regarding vaccine safety are a persistent barrier to vaccine acceptance during pregnancy.
Previous studies on maternal COVID-19 vaccination and birth outcomes have been limited by small sample size (2) or lack of an unvaccinated comparison group. In this retrospective cohort study of live births from eight Vaccine Safety Datalink (VSD) healthcare organizations, the risks of preterm birth (<37 weeks gestation) and small for gestational age (SGA) at birth (birth weight
The risks of preterm and SGA at birth were compared between vaccinated and unvaccinated pregnant women, taking into account time-dependent vaccine exposures and propensity to be vaccinated. Singleton pregnancies with estimated onset or last menstrual period between May 17 and October 24, 2020 were eligible for inclusion.
Among 46,079 pregnant women with live births and available gestational age, 10,064 (21.8%) received ≥1 dose of COVID-19 vaccine during pregnancy and from December 15, 2020 to July 22, 2021; almost all (9,892; 98.3%) were vaccinated during the second or third trimester.
- COVID-19 vaccination during pregnancy was not associated with preterm birth (adjusted hazard ratio [aHR] = 0.91, 95% CI = 0.82–1.01).
- Among 40,627 live births with available birth weight, COVID-19 vaccination during pregnancy was not associated with SGA at birth (aHR = 0.95; 95% CI = 0.87–1.03).
The results did not consistently show an increased risk when stratified by COVID-19 mRNA vaccine dose, or by second or third trimester vaccination, compared with the risk among unvaccinated pregnant women. Due to the small number of exposures during the first trimester, aHRs for vaccination during the first trimester could not be calculated.
These data add to the evidence supporting the safety of the COVID-19 vaccine during pregnancy. To reduce the risk of severe illness associated with COVID-19, CDC recommends the COVID-19 vaccine for women who are pregnant, recently pregnant (including those who are breastfeeding), trying to get pregnant now, or they could get pregnant in the future.
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A co-led Yale study, which looked at more than 40,000 pregnant people, adds new evidence supporting the safety of the COVID-19 vaccine during pregnancy.
The study found that COVID-19 vaccination during pregnancy was not associated with preterm birth or having a small for gestational age (SGA) baby when vaccinated and unvaccinated pregnant women were compared. The trimester in which the vaccine was received and the number of COVID-19 vaccine doses received were also not associated with an increased risk of preterm birth or SGA, the researchers found.
The findings were reported on January 4 by the Centers for Disease Control and Prevention (CDC).
Preterm birth (in which babies are born before 37 weeks) and SGA (in which babies are born smaller than normal for gestational age) have been associated with an increased risk of infant death and disability. For the new study, the authors used data from eight health care organizations participating in the Vaccine Safety Datalink, a project established by the CDC to monitor vaccine safety, to investigate the risk of preterm birth or SGA among vaccinated pregnant women and unvaccinated between 16 and 49 years old. years.
Among those included in the study, 10,064 people, or nearly 22%, received at least one dose of the COVID-19 vaccine during pregnancy, the researchers said. The majority (98.3%) received the vaccine during their second or third trimester; the rest (1.7%) received it during the first trimester of pregnancy.
Nearly 96% of those vaccinated received an mRNA vaccine developed by Pfizer-BioNTech or Moderna.
To date, a few studies have described outcomes among live births after COVID-19 vaccination during pregnancy, the researchers say. The new findings add to evidence that the COVID-19 vaccine is safe during pregnancy.
Research into the factors driving low vaccine uptake among pregnant people has found that the most common concerns have been a lack of information about the safety of the COVID-19 vaccine in pregnant people and potential harm to the fetus. The results of this study speak to both, said Heather Lipkind, associate professor of obstetrics, gynecology and reproductive sciences at Yale School of Medicine and lead author of the study.
“Vaccination against COVID-19 is important to prevent serious illness in pregnant women,” Lipkind said. "With rising rates of COVID-19 in our community, we are encouraging pregnant people to get vaccinated."
Pregnant people, in addition to seeing an increased risk of severe illness and death compared to non-pregnant people, are more likely to require intensive care unit admission, invasive ventilation, and machine-assisted blood oxygenation.
The CDC and the American College of Obstetricians and Gynecologists recommend the COVID-19 vaccine for people who are pregnant, breastfeeding, trying to get pregnant, or who might become pregnant in the future.
