COVID-19 vaccination during pregnancy not linked to preterm birth

There is not a significant association between COVID-19 vaccination and preterm birth, according to a recent study published in Vaccines.

Takeaways

The study found no significant association between COVID-19 vaccination during pregnancy and an increased risk of preterm birth.
Pregnant women, when infected with COVID-19, have a 50% increased risk of preterm birth. Additionally, they are at a higher risk of severe illness and adverse pregnancy outcomes compared to non-pregnant women.
Postpartum COVID-19 vaccination does not increase the risk of adverse perinatal outcomes. The vaccine's potential to reduce COVID-19 infection risk may contribute to a decrease in preterm birth incidence.
The study involved a systematic review of articles published up to 2023, utilizing databases like PubMed, Embase, and Scopus. The eligibility criteria included studies published in English that assessed the association between COVID-19 vaccination during pregnancy and preterm birth.
Various results were reported regarding the risk of preterm birth following vaccination, with odds ratios (ORs) indicating reduced, neutral, and increased risk. However, the overall pooled OR for preterm birth after vaccination was 1.03, suggesting a marginal risk and supporting the conclusion that COVID-19 vaccination during pregnancy is not significantly associated with an increased risk of preterm birth.

Pregnant women have been significantly impacted by the COVID-19 pandemic, as physiological changes during pregnancy often impact immune responses. Compared to non-pregnant women, pregnant women have a significantly increased risk of severe illness and adverse pregnancy outcomes such as preterm birth.

COVID-19 infection has been associated with a 50% increased risk of preterm birth. COVID-19 vaccination during postpartum has also been greatly evaluated, with data indicating the vaccine does not increase the risk of adverse perinatal outcomes. As the vaccine reduces COVID-19 infection risk, it may decrease preterm birth incidence.

To determine the association between COVID-19 vaccination during pregnancy and preterm birth, investigators conducted a systematic review. The PubMed, Embase, and Scopus articles were evaluated for literature published up to 2023.

Search terms related to COVID-19, COVID-19 vaccination, vaccination during pregnancy, maternal health, neonatal outcomes, and preterm birth were used as keywords. Eligibility criteria included being published in English and assessing the association between COVID-19 vaccination during pregnancy and preterm birth.

Studies evaluating this association included pregnant patients vaccinated against COVID-19, measured preterm birth-related outcomes, had clear methodology for evaluating vaccination status and timing, had a detailed explanation on preterm birth assessment, and were a clinical trial, cohort study, case-control study, or case series. Births occurring before 37 weeks’ gestation were considered preterm.

Articles were screened based on abstracts, then underwent full-text review by 2 independent reviewers with a third consulted to settle disagreements. Data extraction was performed by 2 researchers and included study design, participant demographics, vaccine type and dosing, vaccination timing, and outcomes related to post-COVID syndrome.

There were 6 studies published between 2021 and 2022 included in the final analysis. Of studies, 3 were prospective cohort designs and 3 retrospective cohort designs. The studies included 35,612 participants, 227 of whom were vaccinated and 608 unvaccinated.

A range of comorbidities was reported across studies. In one study, hypertensive disorders of pregnancy were reported in 1.1% of participants and gestational diabetes in 9.6%. One study reported obesity in 19.6% of vaccinated patients and 22.4% of unvaccinated patients. Higher rates of previous miscarriage and cesarean delivery were reported in vaccinated women.

The average reported birth weights were 3149 g among infants born to vaccinated mothers and 3207 g among infants born to unvaccinated mothers. Five-minute APGAR scores below 7 were seen in 6.3% and 6.6% of newborns, respectively.

In one study, 96% of infants born to vaccinated mothers were born at 37 weeks of gestation or greater. Vaccination had an odds ratio (OR) of 2.87 for adverse pregnancy outcomes.

Various results were found for preterm birth risk following vaccination, with ORs of 0.59, 1.01, and 1.49 reported. These indicated reduced, neutral, and increased risk, respectively. However, the increased risk was only found for second-trimester vaccination in the single study. Overall, the pooled OR for preterm birth after vaccination was 1.03, indicating a marginal risk.

These results indicated COVID-19 vaccination during pregnancy is not significantly associated with increased preterm birth risk. Investigators concluded this data should inform public health policy and reassure providers and expectant mothers.

Uta M, Craina M, Marc F, Enatescu I. Assessing the impact of COVID-19 vaccination on preterm birth: A systematic review with meta-analysis. Vaccines. 2024;12(1):102. doi:10.3390/vaccines12010102