title: Risk factors and demographics for microtia in South America: a case-control analysis.
abstract: BACKGROUND
  The etiopathogenesis of microtia is still unknown in the majority of the cases, particularly for individuals presenting with isolated microtia. Our aim was to evaluate potential risk factors for this condition using a case-control approach.
  
  
  METHODS
  We analyzed data from 1,194 live births with isolated microtia enrolled in the ECLAMC study (Estudio Colaborativo Latino Americano de Malformaciones Congénitas) from 1982 to 2011 and their respective controls. Odds ratios (ORs) were estimated with logistic regression models along with 95% confidence intervals for the resulting OR estimates controlling for the effects of potential confounders (sex, maternal age, hospital, and year of birth) for an adjusted OR (aOR).
  
  
  RESULTS
  Multiparity was associated with a higher risk of microtia compared with primiparity (aOR, 1.5; 95% confidence interval [CI], 1.2-1.8), with women who had eight or more prior pregnancies having the highest risk (aOR, 2.8; 95% CI, 1.6-5.2). Women who presented with cold-like symptoms were at higher risk for microtia (aOR, 2.2; 95% CI, 1.2-3.9) as well as those that used tobacco or alcohol during pregnancy (aOR, 1.7; 95% CI, 1.1-2.6 and aOR, 1.4; 95% CI, 0.9-2.1, respectively). The association with alcohol use appeared to be limited to those women who reported binge drinking during pregnancy (aOR, 1.4; 95% CI, 0.7-3.1). Cases from hospitals at low altitude (<2500 m) tended to have more severe types of microtia than those from hospitals at high altitude.
  
  
  CONCLUSIONS
  These results support the hypothesis that, in addition to teratogens, other nongenetic risk factors contribute to the occurrence of isolated microtia.
authors.affiliation: Seattle Children's Hospital, Craniofacial Center, Seattle, Washington; University of Washington, Department of Pediatrics, Seattle, Washington.
authors.forename: Daniela V
authors.initials: DV
authors.lastname: Luquetti
authors.forename: Babette S
authors.initials: BS
authors.lastname: Saltzman
authors.forename: Jorge
authors.initials: J
authors.lastname: Lopez-Camelo
authors.forename: Maria da Graça
authors.initials: Mda G
authors.lastname: Dutra
authors.forename: Eduardo E
authors.initials: EE
authors.lastname: Castilla
mesh_terms: D000328:Adult; D000428:Alcohol Drinking / Q000009:adverse effects / Q000453:epidemiology; D016022:Case-Control Studies; D000013:Congenital Abnormalities / Q000453:epidemiology* / Q000209:etiology*; D065817:Congenital Microtia; D004423:Ear / Q000002:abnormalities*; D005260:Female; D006801:Humans; D008297:Male; D008954:Models, Biological; D011247:Pregnancy; D012307:Risk Factors; D013020:South America; D013723:Teratogens / Q000633:toxicity; D064424:Tobacco Use / Q000009:adverse effects / Q000453:epidemiology
chemical_list: D013723:Teratogens
keywords: anotia; ear; epidemiology; microtia; nongenetic risk factors