title: Trivalent inactivated influenza vaccine and spontaneous abortion.
abstract: OBJECTIVE
  To estimate the association between spontaneous abortion and influenza vaccine receipt with a case-control study utilizing data from six health care organizations in the Vaccine Safety Datalink.
  
  
  METHODS
  Women aged 18-44 years with spontaneous abortion during the autumn of 2005 or 2006 were identified using International Classification of Diseases, 9th Revision, Clinical Modification codes. Cases of spontaneous abortion at 5-16 weeks of gestation were confirmed by medical record review; date of fetal demise was based on ultrasound information when available. Control group individuals with a live birth were individually matched to case group individuals by health care organization and date of last menstrual period (LMP). The primary exposure of interest was influenza vaccination during the 28 days preceding the date of spontaneous abortion of the matched pair. Conditional logistic regression models adjusted for maternal age, health care utilization, maternal diabetes, and parity.
  
  
  RESULTS
  Our final analysis included 243 women with spontaneous abortion and 243 matched control group women; 82% of women with spontaneous abortion had ultrasound confirmation of fetal demise. Using clinical diagnosis and ultrasound data, the mean gestational age at fetal demise was 7.8 weeks. Mean ages at LMP of case group women and control group women were 31.7 and 29.3 years, respectively (P<.001). Sixteen women with spontaneous abortion (7%) and 15 (6%) matched control group women received influenza vaccine within the 28-day exposure window. There was no association between spontaneous abortion and influenza vaccination in the 28-day exposure window (adjusted matched odds ratio 1.23, 95% confidence interval 0.53-2.89; P=.63).
  
  
  CONCLUSIONS
  There was no statistically significant increase in the risk of pregnancy loss in the 4 weeks after seasonal inactivated influenza vaccination.
  
  
  METHODS
  II.
authors.affiliation: Epidemiology Research Center, Marshfield Clinic Research Foundation, and Obstetrics and Gynecology, Marshfield Clinic, Marshfield, Wisconsin 5449, USA.
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Irving
authors.forename: Burney A
authors.initials: BA
authors.lastname: Kieke
authors.forename: James G
authors.initials: JG
authors.lastname: Donahue
authors.forename: Maria A
authors.initials: MA
authors.lastname: Mascola
authors.forename: James
authors.initials: J
authors.lastname: Baggs
authors.forename: Frank
authors.initials: F
authors.lastname: DeStefano
authors.forename: T Craig
authors.initials: TC
authors.lastname: Cheetham
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Jackson
authors.forename: Allison L
authors.initials: AL
authors.lastname: Naleway
authors.forename: Jason M
authors.initials: JM
authors.lastname: Glanz
authors.forename: James D
authors.initials: JD
authors.lastname: Nordin
authors.forename: Edward A
authors.initials: EA
authors.lastname: Belongia
mesh_terms: D000022:Abortion, Spontaneous / Q000209:etiology*; D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D005260:Female; D005313:Fetal Death / Q000000981:diagnostic imaging / Q000453:epidemiology; D046689:Fetal Mortality; D005865:Gestational Age; D006801:Humans; D007252:Influenza Vaccines / Q000009:adverse effects*; D016015:Logistic Models; D011247:Pregnancy; D012306:Risk; D014463:Ultrasonography; D015164:Vaccines, Inactivated / Q000009:adverse effects; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines; D015164:Vaccines, Inactivated