title: Maternal prepregnancy body mass index and offspring attention-deficit/hyperactivity disorder: a quasi-experimental sibling-comparison, population-based design.
abstract: High maternal prepregnancy body mass index (BMI) has been associated with increased risk of offspring attention-deficit/hyperactivity disorder (ADHD). However, whether this effect is attributable to maternal or familial level confounds has been little examined.
  
  
  
  The present study sought to examine these associations, utilizing data from the medical records of a health care system which treats 350,000 patients annually and a sibling-comparison design in a sample of 4,682 children born to 3,645 mothers.
  
  
  
  When examining the overall maternal effect, a linear association was observed between maternal prepregnancy BMI and child ADHD [b = 0.04, 95% confidence interval (95% CI) = 0.02-0.06, p = .0003], such that a one-unit (i.e. 1 kg/m2) increase in prepregnancy BMI was associated with a 4% increase in the odds of ADHD (exp b = 1.04). However, when the model was reparameterized to take full advantage of the sibling design to allow for the examination of both maternal and child-specific effects, the child-specific prepregnancy BMI effect was not reliably different from zero (b = -0.08, 95% CI = -0.23 to 0.06, p = .24). In contrast, at the maternal-level, average prepregnancy BMI was a reliably non-zero predictor of child ADHD (b = 0.04, 95% CI = 0.02-0.06, p < .0001) with each one-unit increase in maternal prepregnancy BMI associated with a 4.2% increase in the odds of ADHD (exp b = 1.04, 95% CI = 1.02-1.06).
  
  
  
  The association between maternal prepregnancy BMI and offspring ADHD may be better accounted for by familial or maternal confounds rather than a direct causal effect of BMI.
authors.affiliation: Department of Psychology, Florida International University, Miami, FL, USA.
authors.forename: Erica D
authors.initials: ED
authors.lastname: Musser
authors.affiliation: Education & Workforce Development, RTI International, Research Triangle Park, NC, USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Willoughby
authors.affiliation: Pediatrics, Marshfield Clinic, Marshfield, WI, USA.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Wright
authors.affiliation: Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR, USA.|Department of Biology, University of Portland, Portland, OR, USA.|Department of Psychiatry, Oregon Health & Science University, Portland, OR, USA.
authors.forename: Elinor L
authors.initials: EL
authors.lastname: Sullivan
authors.affiliation: Department of Medicine, Section of Health Promotion & Sports Medicine, Graduate Programs in Human Nutrition, Oregon Health & Science University, Portland, OR, USA.
authors.forename: Diane D
authors.initials: DD
authors.lastname: Stadler
authors.affiliation: Marshfield Clinic Research Foundation, Marshfield, WI, USA.
authors.forename: Brent F
authors.initials: BF
authors.lastname: Olson
authors.affiliation: Marshfield Clinic Research Foundation, Marshfield, WI, USA.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Steiner
authors.affiliation: Department of Psychiatry, Oregon Health & Science University, Portland, OR, USA.
authors.forename: Joel T
authors.initials: JT
authors.lastname: Nigg
mesh_terms: D000328:Adult; D001289:Attention Deficit Disorder with Hyperactivity / Q000453:epidemiology* / Q000209:etiology; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D015146:Midwestern United States / Q000453:epidemiology; D009035:Mothers / Q000706:statistics & numerical data*; D035781:Siblings
keywords: Attention-deficit/hyperactivity disorder; maternal BMI; quasi-experimental design