COVID-19 Vaccination During Pregnancy Doesn’t Increase Peripartum Risks

Mothers who received COVID-19 vaccines during pregnancy saw no increased risk for complications during the period shortly before, during and after giving birth, a new study in Canada found.

The study, published in JAMA, included 97,590 participants who gave birth between Dec. 14, 2020, and Sept. 30, 2021, in Ontario, Canada, 22,660 (23%) of whom received at least 1 dose of COVID-19 vaccine during pregnancy compared with 44,815 who were vaccinated after pregnancy and 30,115 who weren’t vaccinated. The study analyzed data from BORN Ontario, the provincial birth registry, which is linked to Ontario’s COVID-19 immunization database.

“Vaccination was not significantly associated with any increased risk of postpartum hemorrhage, chorioamnionitis, cesarean delivery, NICU admission, or low 5-minute Apgar score,” the study authors wrote. “The results were largely unchanged when stratified according to the number of doses received during pregnancy, vaccine product, or the trimester when dose 1 was received.”

Among the 22,660 who were vaccinated during pregnancy, 99.8% received an mRNA vaccine and 63.6% received their first dose during the third trimester of pregnancy.

Risks were similar among those vaccinated during pregnancy compared with those vaccinated after pregnancy for:

• Postpartum hemorrhage (incidence: 3.0% vs 3.0%; adjusted risk difference, −0.28 per 100 individuals [95% confidence interval, −0.59 to 0.03]; adjusted risk ratio, 0.91 [95% CI, 0.82-1.02]).
• Chorioamnionitis (0.5% vs 0.5%; aRD, −0.04 per 100 individuals [95% CI, −0.17 to 0.09]; aRR, 0.92 [95% CI, 0.70-1.21]).
• Cesarean delivery (30.8% vs 32.2%; aRD, −2.73 per 100 individuals [95% CI, −3.59 to −1.88]; aRR, 0.92 [95% CI, 0.89-0.95]).
• NICU admission (11.0% vs 13.3%; aRD, −1.89 per 100 newborns [95% CI, −2.49 to −1.30]; aRR, 0.85 [95% CI, 0.80-0.90]).
• Low Apgar score (1.8% vs 2.0%; aRD, −0.31 per 100 newborns [95% CI, −0.56 to −0.06]; aRR, 0.84 [95% CI, 0.73-0.97]).

Similar results were found when compared with those who weren’t vaccinated during the study period.

“There is increasing evidence from studies around the world showing that COVID-19 vaccination during pregnancy is not associated with poor pregnancy or birth outcomes, and showing that COVID-19 vaccines are effective at preventing COVID-19 in pregnant mothers and also in their babies in the first few months of life.” lead author Deshayne Fell, PhD, an associate professor in the University of Ottawa’s Faculty of Medicine and a scientist at the CHEO Research Institute, said in a news release.

The study, along with a study involving 157,521 deliveries in Sweden and Norway published in the same issue ofJAMA, offer “the strongest evidence to date regarding the safety of COVID-19 vaccines in pregnancy,” Elyse O. Kharbanda, MD, MPH and Gabriela Vazquez-Benitez, PhD, wrote in an associated editorial.

The study by Magnus et al found no significant association between COVID-19 vaccination during pregnancy and risk for preterm birth (6.2 vs 4.9 per 10,000 pregnancy days), stillbirth (2.1 vs 2.4 per 100,000 pregnancy days), small for gestational age (7.8% vs 8.5%), low Apgar score (1.5% vs 1.6%) or NICU admission (8.5% vs 8.5%).

“The reports by Fell et al and Magnus et al, with their large study populations, thoughtful analytic approach, and lack of any suggestion of safety concerns, are reassuring, especially for pregnant individuals with access to mRNA vaccines in their second or third trimester,” Kharbanda and Vazquez-Benitez wrote. “However, the question remains whether the evidence from these 2 studies will convince those who remain unvaccinated to receive a COVID-19 vaccine during pregnancy. More work is needed to achieve equity in the availability, acceptance, and administration of life-saving interventions such as the COVID-19 vaccines.”

Previous research has shown that pregnant people who are unvaccinated and contract COVID-19 are more likely to experience adverse birth outcomes, even in mild cases.

Some pregnant women have been hesitant to get vaccinated for fear of possible complications. But research shows vaccination is safe and effective during pregnancy, and health officials have urged pregnant women to get vaccinated.