title: Maternal influenza immunization and birth outcomes of stillbirth and spontaneous abortion: a systematic review and meta-analysis.
abstract: Despite strong evidence that maternal influenza vaccination during pregnancy is safe, uptake of influenza vaccination during pregnancy remains low. We identified studies that assessed outcomes of stillbirth or spontaneous abortion after administration of influenza vaccine during pregnancy. We conducted a literature search in November 2013 that yielded 447 total citations. After removal of duplicates and studies deemed not relevant based on the title and abstract, 36 records underwent a full text review and 7 studies were included in the final review. Where possible, adjusted results were included in the meta-analysis. Women in the influenza vaccine group had a lower likelihood of stillbirth (relative risk [RR], 0.73; 95% confidence interval [CI], .55-.96); this association was similar when restricted to the H1N1pdm09 vaccine (RR, 0.69; 95% CI, .53-.90). The pooled estimate for spontaneous abortion was not significant (RR, 0.91; 95% CI, .68-1.22). These analyses add to the evidence base for the safety of influenza vaccination in pregnancy.
authors.affiliation: Department of Epidemiology Hubert Department of Global Health, Rollins School of Public Health, Emory University.
authors.forename: Kristin N
authors.initials: KN
authors.lastname: Bratton
authors.affiliation: Department of Epidemiology Hubert Department of Global Health, Rollins School of Public Health, Emory University.
authors.forename: Melissa T
authors.initials: MT
authors.lastname: Wardle
authors.affiliation: Department of Epidemiology Hubert Department of Global Health, Rollins School of Public Health, Emory University Department of Medicine, Division of Infectious Diseases Influenza Pathogenesis and Immunology Research Center.
authors.forename: Walter A
authors.initials: WA
authors.lastname: Orenstein
authors.affiliation: Department of Epidemiology Hubert Department of Global Health, Rollins School of Public Health, Emory University Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia.
authors.forename: Saad B
authors.initials: SB
authors.lastname: Omer
mesh_terms: D000022:Abortion, Spontaneous / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000009:adverse effects*; D007251:Influenza, Human / Q000517:prevention & control*; D011247:Pregnancy; D050497:Stillbirth / Q000453:epidemiology*; D014611:Vaccination / Q000009:adverse effects* / Q000379:methods / Q000706:statistics & numerical data
chemical_list: D007252:Influenza Vaccines
keywords: influenza vaccine; pregnancy; spontaneous abortion; stillbirth