title: Case-control study of prenatal ultrasonography exposure in children with delayed speech.
abstract: OBJECTIVE
  To determine whether there is an association between prenatal ultrasound exposure and delayed speech in children.
  
  
  METHODS
  Case-control study.
  
  
  METHODS
  Network of community physicians affiliated with the Primary Care Research Unit, University of Calgary.
  
  
  METHODS
  Thirty-four practitioners identified 72 children aged 24 to 100 months who had undergone a formal speech-language evaluation and were found to have delayed speech of unknown cause by a speech-language pathologist. For each case subject the practitioners found two control subjects matched for sex, date of birth, sibling birth order and associated health problems.
  
  
  METHODS
  Rates of prenatal ultrasound exposure and delayed speech.
  
  
  RESULTS
  The children with delayed speech had a higher rate of ultrasound exposure than the control subjects. The findings suggest that a child with delayed speech is about twice as likely as a child without delayed speech to have been exposed to prenatal ultrasound waves (odds ratio 2.8, 95% confidence limit 1.5 to 5.3; p = 0.001).
  
  
  CONCLUSIONS
  An association between prenatal ultrasonography exposure and delayed speech was found. If there is no obvious clinical indication for diagnostic in-utero ultrasonography, physicians might be wise to caution their patients about the vulnerability of the fetus to noxious agents.
authors.affiliation: Department of Surgery, University of Calgary, Alta.
authors.forename: J D
authors.initials: JD
authors.lastname: Campbell
authors.forename: R W
authors.initials: RW
authors.lastname: Elford
authors.forename: R F
authors.initials: RF
authors.lastname: Brant
mesh_terms: D015982:Bias; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007805:Language Development Disorders / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D016017:Odds Ratio; D011247:Pregnancy; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal / Q000009:adverse effects*