Risk of Preterm or Small-for-Gestational-Age Birth After Influenza Vaccination During Pregnancy

Vazquez-Benitez et al, Am J Epidemiol. 2016


Vaccines are increasingly targeted to

A nurse gives a premature baby its soother under a phototherapy lamp, in the Neonatal Intensive Care Unit at the Royal Victoria Hospital in Montreal Monday August 13 2007. (Tyrel Featherstone/THEGAZETTE)

ward women of reproductive age, and vaccines to prevent influenza and pertussis are recommended during pregnancy. Prelicensure clinical trials typically have not included pregnant women, and when they are included, trials cannot detect rare events. Thus, postmarketing vaccine safety assessments are necessary. However, analysis of observational data requires detailed assessment of potential biases. 

Investigators conducting studies to evaluate birth outcomes after maternal vaccination should use statistical approaches to minimize potential biases.