COVID-19 Vaccine Not Associated With Adverse Outcomes in Pregnant Women

COVID-19 vaccination during pregnancy was not associated with any adverse outcomes, according to a review published in Frontiers in Public Health. Neonatal and maternal outcomes were not associated with any potential adverse effects from the COVID-19 vaccine.

Having COVID-19 has been associated with an increased risk of maternal mortality and morbidity during pregnancy. However, clinical trials often exclude pregnant people. This review aimed to compile the available evidence to determine the safety and efficacy of the COVID-19 vaccine for people who were pregnant.

The researchers used MEDLINE, EMBASE, and Cochrane Library for their search on April 5, 2021. Ongoing and completed trials were also searched on clinicaltrials.gov. An updated search was done on May 25, 2022.

Studies that included the association of COVID-19 vaccination with the primary outcomes of stillbirth or neonatal death or the secondary outcomes of miscarriage, congenital anomalies, preterm birth, low birth weight, neonatal intensive care unit (NICU) admission or hospitalization, cesarean delivery, and postpartum hemorrhage were included in the review.

Studies were excluded if they were not peer reviewed, included an intervention or control group that had received the first COVID-19 vaccination, were case-control studies, included participants from an included article with a larger sample size, or were case reports. Data extracted from the studies included the year of publication, geographical region, sample size, outcomes of interest, vaccination timing, and vaccination type. All studies were evaluated for quality using the Newcastle-Ottawa Scale. A random-effects meta-analysis was conducted.

There were 43 observational studies included in the systematic review, which accounted for 599,956 pregnant people. There were also 23 studies included in the meta-analysis. There were 369,397 people from Europe; 229,576 from the American region, and 2 studies that included pregnant people of the West Pacific region. There were 130,445 people who had received vaccines, of which 73.9% received BNT162b2, 23.7% received mRNA-1273, and 2.4% who received other types; 18.3%, 40.5%, and 41.2% were vaccinated in their first, second, and third trimester, respectivelty.

The incidence of stillbirth or neonatal death in the 10 studies that reported the outcome was 0.0% to 0.9% in vaccinated pregnant people. COVID-19 vaccination also was associated with a 26% reduced risk of stillbirth or neonatal death within the first 28 days after the birth when vaccinated during pregnancy (pooled odds ratio [OR], 0.74; 95% CI, 0.60-0.92). The pooled OR was not robust when restricting the studies to those who did not contract COVID-19 after vaccination (OR, 0.95; 95% CI, 0.58-1.56) or studies that adjusted for baseline characteristics (OR, 0.77; 95% CI, 0.42-1.38).

Vaccination for COVID-19 was not associated with fetal or neonatal congenital anomalies (OR, 0.83; 95% CI, 0.63-1.08) with the pooled risk not increasing (OR, 0.73; 95% CI, 0.52-1.01). There also was no significant difference between the vaccinated and unvaccinated groups (OR, 0.98; 95% CI, 0.90-1.06) for pregnant people who reported preterm birth. COVID-19 vaccination during pregnancy was also not associated with NICU admission (OR, 0.94; 95% CI, 0.84-1.04).

Birthweight was also not affected by COVID-19 vaccination (mean difference [MD], 0.81 g; 95% CI, –15.55 to 17.18) or gestational age at time of delivery (MD, –0.05 week; 95 % CI, –0.11 to 0.01). The risk of miscarriage had an overall OR of 0.99 (95% CI, 0.88-1.11). Risk of cesarean delivery did not increase following COVID-19 vaccination (OR, 1.07; 95% CI, 0.96-1.19), but risk of postpartum hemorrhage was close to the significance threshold (OR, 0.91; 95% CI, 0.81-1.01).

The level of evidence in this analysis is limited due to the observational studies included, and baseline characteristics were not balanced in most studies. Also, vaccines from 4 manufacturers made up 90% of the vaccines taken and the majority of participants were vaccinated after the period of greatest risk.

The researchers concluded that COVID-19 vaccination during pregnancy was associated with a reduced risk of stillbirth or newborn death and that the vaccine was also not associated with any adverse neonatal or maternal outcomes.

Reference

Ding C, Liu Y, Pang W, Zhang D, Wang K, Chen Y. Associations of COVID-19 vaccination during pregnancy with adverse neonatal and maternal outcomes: a systematic review and meta-analysis. Front Public Health. Published online January 30, 2023. doi:10.3389/fpubh.2023.1044031