title: Prenatal ultrasound and childhood autism: long-term follow-up after a randomized controlled trial of first- vs second-trimester ultrasound.
abstract: OBJECTIVE
  To analyze whether the frequency of autism spectrum disorder (ASD) in a cohort of Swedish children differs between those exposed to ultrasound in the 12(th) week and those exposed to ultrasound in the 18(th) week of gestation.
  
  
  METHODS
  The study cohort consisted of approximately 30 000 children born between 1999 and 2003 to mothers who had been randomized to a prenatal ultrasound examination at either 12 or 18 weeks' gestation as part of the framework for a study on nuchal translucency screening. The outcome measure in the present study was the rate of ASD diagnoses among the children. Information on ASD diagnoses was based on data from the Swedish social insurance agency concerning childcare allowance granted for ASD.
  
  
  RESULTS
  Between 1999 and 2003, a total of 14 726 children were born to women who underwent a 12-week ultrasound examination and 14 596 to women who underwent an 18-week ultrasound examination. Of these, 181 (1.2%) and 176 (1.2%) children, respectively, had been diagnosed with ASD. There was no difference in ASD frequency between the early and late ultrasound groups.
  
  
  CONCLUSIONS
  Women subjected to at least one prenatal ultrasound examination at either 12 or 18 weeks' gestation had children with similar rates of ASD. However, this result reflects routine care 10-15 years ago in Sweden. Today, higher intensity ultrasound scans are performed more frequently, at earlier stages during pregnancy and for non-medical purposes, implying longer exposure time for the fetus. This change in the use of ultrasound necessitates further follow-up study of the possible effects that high exposure to ultrasound during the gestational period has on the developing brain. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.
authors.affiliation: Gillberg Neuropsychiatry Centre, Gothenburg University, Gothenburg, Sweden.|Department of Pediatrics, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Höglund Carlsson
authors.affiliation: Department of Obstetrics and Gynaecology, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Saltvedt
authors.affiliation: Department of Molecular Medicine and Surgery and Centre for Molecular Medicine, Karolinska Institutet and Department of Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: B-M
authors.initials: BM
authors.lastname: Anderlid
authors.affiliation: Gillberg Neuropsychiatry Centre, Gothenburg University, Gothenburg, Sweden.|Department of Psychology, Stockholm University, Stockholm, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Westerlund
authors.affiliation: Gillberg Neuropsychiatry Centre, Gothenburg University, Gothenburg, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Gillberg
authors.affiliation: Center for Fetal Medicine, Karolinska University Hospital and Division of Clintec, Karolinska Institutet, Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Westgren
authors.affiliation: Gillberg Neuropsychiatry Centre, Gothenburg University, Gothenburg, Sweden.
authors.forename: E
authors.initials: E
authors.lastname: Fernell
mesh_terms: D000328:Adult; D000067877:Autism Spectrum Disorder / Q000453:epidemiology* / Q000209:etiology; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D008297:Male; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology* / Q000503:physiopathology; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D016216:Ultrasonography, Prenatal / Q000009:adverse effects
keywords: autism; children; early vs late; outcome; prenatal ultrasound