OBJECTIVE: To compare risks for adverse obstetric events between females who did and did not receive trivalent inactivated influenza vaccine during pregnancy.
METHOD: This retrospective, observational cohort study was conducted at seven Vaccine Safety Datalink sites. Pregnancies were identified from administrative and claims data using a validated algorithm. Females vaccinated while pregnant from 2002 to 2009 were matched one-to-two with replacement to unvaccinated pregnant females. Using a generalized estimating equation method with a Poisson distribution and log link, we evaluated the association of trivalent inactivated influenza vaccine with 13 outcomes. Given our large sample size and multiple comparisons (19 contrasts), a cutoff for significance of P<.005 was selected a priori.
RESULTS: Our cohort included 74,292 vaccinated females matched on age, site, and pregnancy start date with 144,597 unvaccinated females. We did not observe increased risks within 42 days of vaccination for hyperemesis, chronic hypertension, gestational hypertension, gestational diabetes, proteinuria, or urinary tract infection. Using a risk window from vaccination through pregnancy end, we did not observe increased risks after vaccination for proteinuria, urinary tract infection, gestational hypertension, preeclampsia or eclampsia, chorioamnionitis, puerperal infection, venous complications, pulmonary embolism, or peripartum cardiomyopathy. A reduced risk for gestational diabetes after vaccination was detected (adjusted hazard rate ratio 0.88, 95% confidence interval 0.83–0.93), likely as a result of healthy vaccine bias or earlier detection among vaccinees.
CONCLUSION: In this large cohort, influenza vaccination during pregnancy was not associated with increased risks for medically attended adverse obstetric events.
LEVEL OF EVIDENCE: II
Receipt of trivalent influenza vaccine during pregnancy is not associated with adverse obstetric events.
Health Partners Institute for Education and Research, Minneapolis, Minnesota; the Department of Obstetrics and Gynecology, Yale University, New Haven, Connecticut; the Center for Health Research, Kaiser Permanente Northwest, Portland, Oregon; and the Department of Population Medicine, Harvard Pilgrim Health Care Institute & Harvard Medical School, Boston, Massachusetts.
Corresponding author: Elyse Olshen Kharbanda, MD, MPH, Health Partners Institute for Education and Research, PO Box 1524, MS 21111R, Minneapolis, MN 55425; e-mail: Elyse.O.Kharbanda@HealthPartners.com.
Supported by a subcontract with America's Health Insurance Plans under contract 200-2002-00732 from the Centers for Disease Control and Prevention.
The authors thank Beth Molitor, MBA, Leslie Kuckler, MPH, Rachel Gold, PhD, MPH, Karen Riedlinger, MPH, and Samantha Kurosky, MPH, for assistance with data collection. These contributors were all supported by a subcontract with America's Health Insurance Plans under contract 200-2002-00732 from the Centers for Disease Control and Prevention.
Financial Disclosure Dr. Naleway has received research funding from GlaxoSmithKline. The other authors did not report any potential conflicts of interest.