The most popular COVID-19 vaccines are safe to use in pregnancy, a large, new Canadian study has concluded.
About 4% of pregnant women given an mRNA vaccine had a significant health event within a week of their first dose, and about 7% did after dose two, according to data gathered from more than 191,000 Canadian women.
By comparison, 3% of unvaccinated pregnant women reported similar significant health events, which were defined as an illness that made the person miss work or school, required a medical consultation, or prevented them from participating in regular daily activities.
The most common significant health events after dose two in pregnant women were a general feeling of being unwell, headache or migraine, and respiratory tract infection.
Among a control group of vaccinated but not pregnant people, about 6% reported a health event after the first dose and 11% after the second, according to the report published online Aug. 11 in The Lancet Infectious Diseases.
The study, which was led by Manish Sadarangani, of the Vaccine Evaluation Center at BC Children's Hospital Research Institute in Vancouver, is one of the first to compare vaccine side effects between vaccinated pregnant women, unvaccinated pregnant women, and a third group that was vaccinated but not pregnant.
Serious health events — defined as requiring an emergency department visit or hospitalization — were rare in all groups (less than 1%).
Miscarriage or stillbirth was the most frequently reported adverse pregnancy outcome, but there was no significant difference between the rates of those in vaccinated and unvaccinated women, the study authors reported in a journal news release.
About 2% of unvaccinated pregnant women and 1.5% of vaccinated pregnant women experienced a miscarriage or stillbirth within seven days after dose one of any mRNA vaccine.
The findings “are consistent with and add to the growing body of evidence that COVID-19 mRNA vaccines are safe during pregnancy,” claimed a commentary that accompanied the new study.
The U.S. Centers for Disease Control and Prevention has more about COVID-19 vaccines.
SOURCE: The Lancet Infectious Diseases, news release, Aug. 11, 2022