title: Maternal smoking during pregnancy, other prenatal and perinatal factors, and the risk of Legg-Calvé-Perthes disease.
abstract: OBJECTIVE
  The causes of Legg-Calvé-Perthes disease are largely unknown, but this pediatric disease seems to result from interruption of the blood supply to the proximal femur and is considered a vascular disease. Because maternal smoking during pregnancy influences fetal development and is associated with cardiovascular diseases in offspring, we hypothesized that this exposure is a risk for Legg-Calvé-Perthes disease and also investigated other markers of impaired fetal development and early-life exposures.
  
  
  METHODS
  The Swedish Inpatient Register identified 852 individuals with a diagnosis of Legg-Calvé-Perthes disease from 1983 to 2005, individually matched by year of birth, age, sex, and region of residence with 4432 randomly selected control subjects. Linkage with the Swedish Medical Birth Register provided information on prenatal factors, including maternal smoking. Conditional logistic regression examined associations of maternal smoking during pregnancy and the other measures with the risk of Legg-Calvé-Perthes disease in offspring, adjusted for socioeconomic index and other potential confounding factors.
  
  
  RESULTS
  Maternal smoking during pregnancy was associated with an increased Legg-Calvé-Perthes disease risk, and heavy smoking was associated with a risk increase of almost 100%. Very low birth weight and cesarean section were independently associated with approximately 240% and 36% increases in the risk of Legg-Calvé-Perthes disease, respectively.
  
  
  CONCLUSIONS
  Maternal smoking during pregnancy and other factors indicated by impaired fetal development may be associated with an increased risk of Legg-Calvé-Perthes disease.
authors.affiliation: Clinical Epidemiology Unit, Department of Medicine, Karolinska University Hospital, Stockholm, Sweden. shahram.bahmanyar@ki.se
authors.forename: Shahram
authors.initials: S
authors.lastname: Bahmanyar
authors.forename: Scott M
authors.initials: SM
authors.lastname: Montgomery
authors.forename: Rüdiger J
authors.initials: RJ
authors.lastname: Weiss
authors.forename: Anders
authors.initials: A
authors.lastname: Ekbom
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D017668:Age of Onset; D001724:Birth Weight; D016022:Case-Control Studies; D015984:Causality; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D016001:Confidence Intervals; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D015994:Incidence; D007223:Infant; D007873:Legg-Calve-Perthes Disease / Q000453:epidemiology* / Q000503:physiopathology; D016015:Logistic Models; D008297:Male; D018811:Maternal Exposure / Q000706:statistics & numerical data*; D016017:Odds Ratio; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000175:diagnosis / Q000453:epidemiology*; D011336:Probability; D012016:Reference Values; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D017678:Sex Distribution; D012907:Smoking / Q000453:epidemiology*; D013548:Sweden / Q000453:epidemiology