Risk of Preterm or Small-for-Gestational-Age Birth After Influenza Vaccination During Pregnancy: Caveats When Conducting Retrospective Observational Studies

Details

• Alternative Title:
  Am J Epidemiol
• Personal Author:
  Vazquez-Benitez, Gabriela ; Kharbanda, Elyse O. ; Naleway, Allison L. ; Lipkind, Heather ; Sukumaran, Lakshmi ; McCarthy, Natalie L. ; Omer, Saad B. ; Qian, Lei ; Xu, Stanley ; Jackson, Michael L. ; Vijayadev, Vinutha ; Klein, Nicola P. ; Nordin, James D.
• Description:
  Vaccines are increasingly targeted toward 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. Using data from 8 Vaccine Safety Datalink sites in the United States, we analyzed the association of monovalent H1N1 influenza vaccine (MIV) during pregnancy with preterm birth (<37 weeks) and small-for-gestational-age birth (birth weight < 10th percentile). The cohort included 46,549 pregnancies during 2009-2010 (40% of participants received the MIV). We found potential biases in the vaccine-birth outcome association that might occur due to variable access to vaccines, the time-dependent nature of exposure to vaccination within pregnancy (immortal time bias), and confounding from baseline differences between vaccinated and unvaccinated women. We found a strong protective effect of vaccination on preterm birth (relative risk = 0.79, 95% confidence interval: 0.74, 0.85) when we ignored potential biases and no effect when accounted for them (relative risk = 0.91; 95% confidence interval: 0.83, 1.0). In contrast, we found no important biases in the association of MIV with small-for-gestational-age birth. Investigators conducting studies to evaluate birth outcomes after maternal vaccination should use statistical approaches to minimize potential biases.
• Subjects:
  Adult Bias (Epidemiology) Comorbidity Databases, Factual Female Humans Infant, Newborn Infant, Small For Gestational Age Influenza, Human Influenza A Virus, H1N1 Subtype Influenza Vaccines Maternal Age Observational Studies As Topic Pregnancy Pregnancy Complications, Infectious Pregnancy Outcome Pregnancy Trimesters Premature Birth Prevalence Product Surveillance, Postmarketing Propensity Score Retrospective Studies Risk Assessment Time Factors Young Adult

  More +
• Source:
  Am J Epidemiol. 184(3):176-186.
• Pubmed ID:
  27449414
• Pubmed Central ID:
  PMC5003116
• Document Type:
  Journal Article
• Funding:
  CC999999/Intramural CDC HHS/United States ; UL1 TR001863/TR/NCATS NIH HHS/United States
• Place as Subject:
  United States
• Volume:
  184
• Issue:
  3
• Collection(s):
  CDC Public Access
• Main Document Checksum:
  urn:sha256:7881acb40a97bf8938f336e72b253e77f73ea1426d96a7d71b184976039b6227
• Download URL:
  https://stacks.cdc.gov/view/cdc/41123/cdc_41123_DS1.pdf
• File Type:
  [PDF - 665.37 KB ]