A recent prospective cohort study found that regardless of the trimester of vaccination, women who received the influenza and pertussis vaccines did not have adverse birth outcomes compared with unvaccinated mothers.
Although both vaccines were previously considered safe during pregnancy, no large-scale maternal or infant perinatal safety data were available, researchers said. WHO’s Global Advisory Committee on Vaccine Safety specifically cited a lack of data regarding the safety of the inactivated influenza vaccine (IIV) given during the first trimester of pregnancy.
“Safety data for women and infants where both IIV and pertussis vaccines have been received during pregnancy are also scarce,” the researchers wrote.
Researchers compared a range of birth outcomes between vaccinated and unvaccinated women who were enrolled in the Australian FluMum study, which was conducted in maternity hospitals in 6 participating sites in Australia from 2012 to 2015.
The latest analysis, which included almost 9,000 women, showed that infants born from mothers who received IIV during pregnancy did not have an elevated risk for preterm birth (HR = 1.10; 95% CI, 0.92-1.31; P = .28), low birth weight (HR, 1.05; 95% CI, 0.76-1.44; P = .77), or being small for gestational age (HR = 0.99; 95% CI, 0.86-1.15; P = .94).
The researchers also conducted sensitivity analyses in a subgroup of women who received pertussis vaccination during pregnancy to assess whether associations between IIV and adverse birth outcomes were maintained after adjusting for pertussis vaccination. This analysis yielded similar results, they said.
In addition, “There were no statistically significant differences in median gestation at birth of infants nor differences in mean birthweight of infants between unvaccinated and IIV-vaccinated pregnant women regardless of the trimester an IIV was received,” they wrote. – by Erin Michael
Disclosures: The authors report no relevant financial disclosures.