In a recent study published in BMJ Global Health, a team of researchers conducted a systematic review of major databases and a meta-analysis to examine the reactogenicity and impact of coronavirus disease 2019 (COVID-19) vaccines on pregnancy outcomes related to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections among women in perinatal or pregnancy stages.

Study: Effectiveness and safety of COVID-19 vaccines on maternal and perinatal outcomes: a systematic review and meta-analysis. Image Credit: Anuta23/Shutterstock.com

Background

Research suggests that women who are pregnant are more vulnerable to severe SARS-CoV-2 infections, resulting in substantial morbidity and a higher risk of mortality as compared to women of similar age who are not pregnant.

While the COVID-19 vaccine has been the single most effective intervention in limiting the spread of the pandemic and decreasing the severity of infections, a majority of the phase III trials for various COVID-19 vaccines did not include pregnant women, leading to a lack of clarity about the efficacy and safety of COVID-19 vaccination among pregnant women.

Concerns about the safety of COVID-19 vaccines have also resulted in a reluctance among pregnant women to avail of the vaccine.

Furthermore, existing reviews and observational studies have focused only on maternal infection and short-term outcomes or on specific countries or regions, making the findings less relevant and difficult to apply globally.

About the study

In the present study, the researchers conducted a systematic review to comprehensively assess the impact of any COVID-19 vaccine on outcomes related to SARS-CoV-2 infections, reactogenicity, or maternal and infant health when administered to women before or during pregnancy.

All major databases, including websites and preprint servers that contained studies on COVID-19, were searched for relevant studies reporting on the impact of COVID-19 on pregnant women. The researchers also contacted groups conducting surveillance studies among pregnant women who had received the COVID-19 vaccine.

The review included studies with comparative cohorts and a test-negative design that reported both unadjusted and adjusted effects of the COVID-19 vaccine on women who received it either before or during their pregnancy.

The study population in these studies consisted of pregnant women exhibiting symptoms similar to COVID-19, and the examined outcomes included SARS-CoV-2 infections in mothers and outcomes related to maternal hospital admissions. The outcomes also included COVID-19-like illness in the neonates.

Women who had tested positive for SARS-CoV-2 were included in the case-cohort, while those that did not were in the control cohort. The vaccination status of the individuals in both cohorts was assessed.

The information extracted from the studies consisted of the study design; the SARS-CoV-2 variant that was predominant at the time; the study setting; adjustment variables such as body mass index, age, gestational age, diabetes, educational levels, and hypertension; the vaccine type and platform; number of vaccine doses; and stage of pregnancy during vaccination.

Infection-related outcomes extracted from the studies included the number of vaccinated or unvaccinated women; maternal SARS-CoV-2 diagnosed before pregnancy; hospital admission, severe COVID-19, or death due to COVID-19 among mothers; and outcomes in offspring such as infection within six months of birth.

Pregnancy-related outcomes in mothers included preterm birth, miscarriage, postpartum hemorrhage, cesarian section, hypertensive disorders, and gestational diabetes. Outcomes in offspring comprised admission to the neonatal intensive care unit (ICU), stillbirth, small size for gestational age, and neonatal death.

Results

The study found that COVID-19 vaccines effectively protected pregnant women from SARS-CoV-2 infections and associated complications with no serious adverse effects. COVID-19 vaccination also appeared to lower the risk of hypertensive disorders among pregnant women and the need for a cesarian section or admission to the neonatal ICU.

The commonly reported side effect after vaccination was pain at the injection site. The meta-analysis reported that pregnant women who had completed the COVID-19 vaccination regimen had 61% lower odds of getting SARS-CoV-2 infection during their pregnancy and 94% lower probability of requiring hospital admission due to COVID-19.

The adjusted cohort studies showed that there was a 12% lower risk of hypertensive disorders during the pregnancy and a 9% lower probability of cesarian section among vaccinated pregnant women. Infants born to vaccinated women also had an 8% reduction in the need for admission to neonatal ICU.

Conclusions

Overall, the study found that COVID-19 vaccinations administered to mothers either before or during the pregnancy had no adverse outcomes related to the pregnancy or the offspring.

Furthermore, it significantly reduced the risk of severe COVID-19 requiring hospital admission and the risk of SARS-CoV-2 infections among pregnant women. COVID-19 vaccines also lowered the risk of pregnancy-related hypertension or the need for cesarian section or neonatal ICU admission.