title: Quantifying the impact of gestational diabetes mellitus, maternal weight and race on birthweight via quantile regression.
abstract: BACKGROUND
  Quantile regression, a robust semi-parametric approach, was used to examine the impact of gestational diabetes mellitus (GDM) across birthweight quantiles with a focus on maternal prepregnancy body mass index (BMI) and gestational weight gain (GWG).
  
  
  METHODS
  Using linked birth certificate, inpatient hospital and prenatal claims data we examined live singleton births to non-Hispanic white (NHW, 135,119) and non-Hispanic black (NHB, 76,675) women in South Carolina who delivered 28-44 weeks gestation in 2004-2008.
  
  
  RESULTS
  At a maternal BMI of 30 kg/m² at the 90(th) quantile of birthweight, exposure to GDM was associated with birthweights 84 grams (95% CI 57, 112) higher in NHW and 132 grams (95% CI: 104, 161) higher in NHB. Results at the 50(th) quantile were 34 grams (95% CI: 17, 51) and 78 grams (95% CI: 56, 100), respectively. At a maternal GWG of 13.5 kg at the 90(th) quantile of birthweight, exposure to GDM was associated with birthweights 83 grams (95% CI: 57, 109) higher in NHW and 135 grams (95% CI: 103, 167) higher in NHB. Results at the 50(th) quantile were 55 grams (95% CI: 40, 71) and 69 grams (95% CI: 46, 92), respectively.
  
  
  CONCLUSIONS
  Our findings indicate that GDM, maternal prepregnancy BMI and GWG increase birthweight more in NHW and NHB infants who are already at the greatest risk of macrosomia or being large for gestational age (LGA), that is those at the 90(th) rather than the median of the birthweight distribution.
authors.affiliation: Department of Public Health Sciences, Medical University of South Carolina, Charleston, South Carolina, United States of America.
authors.forename: Caitlyn N
authors.initials: CN
authors.lastname: Ellerbe
authors.forename: Mulugeta
authors.initials: M
authors.lastname: Gebregziabher
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Korte
authors.forename: Jill
authors.initials: J
authors.lastname: Mauldin
authors.forename: Kelly J
authors.initials: KJ
authors.lastname: Hunt
mesh_terms: D000328:Adult; D001724:Birth Weight; D015331:Cohort Studies; D016640:Diabetes, Gestational / Q000453:epidemiology / Q000503:physiopathology*; D005006:Ethnicity; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009765:Obesity / Q000150:complications*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000209:etiology*; D044469:Racial Groups / Q000706:statistics & numerical data*; D013022:South Carolina / Q000453:epidemiology; D015430:Weight Gain