The team also compared the risk of preterm delivery in vaccinated versus unvaccinated women. While the team did observe a slight increase in preterm delivery rates among pregnant women who received the H1N1 vaccine specifically during the 2009 - 2010 season, vaccinated women overall only delivered an average of two days earlier compared to the unvaccinated group. For those vaccinated during the 2010 - 2011 season, the situation was reversed, and vaccinated women were less likely to deliver a preterm baby.
The other VAMPSS research team from UC San Diego followed 1,032 pregnant women across the U.S. and Canada who either chose to receive an influenza vaccine or were not vaccinated during one of the three seasons from 2009 - 2012. Women were recruited through MotherToBaby, a service of the non-profit Organization of Teratology Information Specialists (OTIS) that provides counseling to the public about pregnancy and breastfeeding exposures. Researchers found that women vaccinated during pregnancy were no more likely to experience miscarriage, have a baby born with a birth defect, or have a baby born smaller than normal compared with those who did not receive a vaccination. In addition, those who were vaccinated delivered infants three days earlier than unvaccinated women.
"The overall results of the study were quite reassuring about the safety of the flu vaccine formulations that contained the pandemic H1N1 strain given in these three seasons," said Christina Chambers, PhD, lead investigator of UC San Diego's team. "We believe our study's results can help women and their doctors become better informed about the benefits and risks of vaccination during pregnancy."
|Contact: Gina DiGravio|
Boston University Medical Center