title: X-ray exposure in utero and school performance: a population-based study of X-ray pelvimetry.
abstract: OBJECTIVE
  To investigate the association between exposure to ionising radiation from pelvimetric examinations in utero and school performance.
  
  
  METHODS
  This was a population-based cohort study comprising 46,066 children born in the county of Östergötland, Sweden, from 1980 through 1990. Through record linkage between Swedish registers, children exposed in utero to X-ray pelvimetry examination were compared to other children born in the same county during the study period, as well as to their unexposed siblings. Outcome variable was primary school grades, expressed in centiles and calculated through linear regression.
  
  
  RESULTS
  In the univariate analysis, children exposed to X-ray pelvimetry in utero had higher school grades compared to unexposed children (point estimate 3 centiles, 95% confidence interval [CI]: 1.5 to 4.6). When sex, mother's education and income, birth order, and birth position were included in the analysis; however, the difference was reduced and the association was no longer statistically significant (PE 1.4, 95% CI: -0.1 to 2.8). Comparing exposed children with their siblings showed no statistical difference in univariate analysis or in multivariate analysis.
  
  
  CONCLUSIONS
  No suggestion was found of a negative effect on school performance from in utero exposure of diagnostic X-ray pelvimetry.
authors.affiliation: Clinical Epidemiology Unit, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden; Department of Clinical Sciences at Danderyds Hospital, Karolinska Institutet, Stockholm, Sweden. Electronic address: Arvid.nordenskjold@ki.se.
authors.forename: A C
authors.initials: AC
authors.lastname: Nordenskjöld
authors.affiliation: Department of Economics, Stockholm University, Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Palme
authors.affiliation: Clinical Epidemiology Unit, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden; Department of Neuroradiology, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Kaijser
mesh_terms: D002648:Child; D004522:Educational Status; D005260:Female; D006801:Humans; D008297:Male; D010387:Pelvimetry / Q000009:adverse effects / Q000379:methods; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology*; D013548:Sweden / Q000453:epidemiology; D014965:X-Rays / Q000009:adverse effects