title: Influenza H1N1 vaccination and adverse pregnancy outcome.
abstract: Although vaccines against influenza can reduce maternal morbidity and mortality, large-scale data on adverse effects in the offspring are scarce. Historical cohort study in Stockholm County, Sweden. We linked H1N1 vaccination data (Pandemrix(®), a mono-valent AS03 adjuvanted H1N1 vaccine) with pregnancy and birth data from 21,087 women with singleton offspring conceived between February 2009 and January 2010 (vaccinated during pregnancy: n = 13,297 vs. unvaccinated: n = 7,790). Data were analysed by conceptualizing the observational cohort as a series of nested cohorts defined at each week of gestation. Logistic regression estimated odds ratios (ORs) for low birth weight (LBW, <2,500 g), preterm birth (<37 completed weeks), small-for-gestational age (SGA, <10th percentile of the gestational age-specific birth weight within the cohort), low 5-min Apgar score (<7), and caesarean section. Data were adjusted for potential confounders, including maternal age, body mass index, smoking, parity, civil status and comorbidities. Compared with infants of non-vaccinated women, infants of vaccinated women had similar adjusted ORs (95 % CI) for LBW (0.91; 0.79-1.04), preterm birth (0.99; 0.89-1.10), SGA (0.97; 0.90-1.05), low Apgar score (1.05, 0.84-1.31), and a marginal risk reduction for caesarean section (0.94, 0.89-0.99). H1N1 vaccination during pregnancy, using an AS03-adjuvanted vaccine, does not appear to adversely influence offspring risks of LBW, preterm birth, SGA, or low Apgar score. Our results suggest that this vaccine is safe for the offspring when used in different stages of pregnancy.
authors.affiliation: Clinical Epidemiology Unit, Department of Medicine, Karolinska Institutet, Stockholm, Sweden. jonasludvigsson@yahoo.com
authors.forename: Jonas F
authors.initials: JF
authors.lastname: Ludvigsson
authors.forename: Daniela
authors.initials: D
authors.lastname: Zugna
authors.forename: Sven
authors.initials: S
authors.lastname: Cnattingius
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Richiardi
authors.forename: Anders
authors.initials: A
authors.lastname: Ekbom
authors.forename: Åke
authors.initials: Å
authors.lastname: Örtqvist
authors.forename: Ingemar
authors.initials: I
authors.lastname: Persson
authors.forename: Olof
authors.initials: O
authors.lastname: Stephansson
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D007114:Immunization / Q000706:statistics & numerical data; D007230:Infant, Low Birth Weight; D053118:Influenza A Virus, H1N1 Subtype; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000009:adverse effects; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control* / Q000821:virology; D016015:Logistic Models; D008423:Maternal Age; D016017:Odds Ratio; D011247:Pregnancy; D011256:Pregnancy Outcome; D011264:Pregnancy Trimesters; D047928:Premature Birth / Q000453:epidemiology; D012959:Socioeconomic Factors; D013548:Sweden / Q000453:epidemiology; D014611:Vaccination; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines