title: Environmental risk factors by gender associated with attention-deficit/hyperactivity disorder.
abstract: BACKGROUND
  Early environmental risk factors associated with attention-deficit/hyperactivity disorder (ADHD) have been increasingly suggested. Our study investigates the maternal, pregnancy, and newborn risk factors by gender for children prescribed stimulant medication for treatment of ADHD in Western Australia.
  
  
  METHODS
  This is a population-based, record linkage case-control study. The records of all non-Aboriginal children and adolescents born in Western Australia and aged <25 years who were diagnosed with ADHD and prescribed stimulant medication (cases = 12,991) were linked to the Midwives Notification System (MNS) to obtain maternal, pregnancy, and birth information. The control population of 30,071 children was randomly selected from the MNS.
  
  
  RESULTS
  Mothers of children with ADHD were significantly more likely to be younger, be single, have smoked in pregnancy, have labor induced, and experience threatened preterm labor, preeclampsia, urinary tract infection in pregnancy, or early term delivery irrespective of the gender of the child, compared with the control group. In the fully adjusted model, a novel finding was of a possible protective effect of oxytocin augmentation in girls. Low birth weight, postterm pregnancy, small for gestational age infant, fetal distress, and low Apgar scores were not identified as risk factors.
  
  
  CONCLUSIONS
  Smoking in pregnancy, maternal urinary tract infection, being induced, and experiencing threatened preterm labor increase the risk of ADHD, with little gender difference, although oxytocin augmentation of labor appears protective for girls. Early term deliveries marginally increased the risk of ADHD. Studies designed to disentangle possible mechanisms, confounders, or moderators of these risk factors are warranted.
authors.affiliation: MB, BS, FRACP, Telethon Institute for Child Health Research, PO Box 855, West Perth, Western Australia 6872. desirees@ichr.uwa.edu.au.
authors.forename: Desiree
authors.initials: D
authors.lastname: Silva
authors.forename: Lyn
authors.initials: L
authors.lastname: Colvin
authors.forename: Erika
authors.initials: E
authors.lastname: Hagemann
authors.forename: Carol
authors.initials: C
authors.lastname: Bower
mesh_terms: D000293:Adolescent; D000328:Adult; D001034:Apgar Score; D001289:Attention Deficit Disorder with Hyperactivity / Q000209:etiology* / Q000517:prevention & control; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004777:Environment; D005260:Female; D006801:Humans; D007223:Infant; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight; D007751:Labor, Induced; D016015:Logistic Models; D008297:Male; D008425:Maternal Behavior; D015999:Multivariate Analysis; D016017:Odds Ratio; D011247:Pregnancy; D011248:Pregnancy Complications; D011297:Prenatal Exposure Delayed Effects / Q000209:etiology; D012307:Risk Factors; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects; D014904:Western Australia; D055815:Young Adult
keywords: ADHD; birth weight; gestational age; risk factors; smoking in pregnancy