title: Obstetric conditions and the placental weight ratio.
abstract: BACKGROUND
  To elucidate how obstetric conditions are associated with atypical placental weight ratios (PWR)s in infants born: (a) ≥37 weeks gestation; (b) at ≥33 but <37 weeks gestation; and (c) <33 weeks gestation.
  
  
  METHODS
  The study included all in-hospital singleton births in London, Ontario between June 1, 2006 and March 31, 2011. PWR was assessed as <10th or >90th percentile by gestational age-specific local population standards. Multivariable analysis was carried out using multinomial logistic regression with blockwise variable entry in order of temporality.
  
  
  RESULTS
  Baseline factors and maternal obstetric conditions associated with PWR <10th percentile were: increasing maternal height, overweight and obese body mass indexes (BMI), large for gestational age infants, smoking, and gestational diabetes. Obstetric factors associated with PWR >90th percentile were: underweight, overweight and obese BMIs, smoking, preeclampsia, placenta previa, and placental abruption. In particular, indicators of hypoxia and altered placental function were generally associated with elevated PWR at all gestations.
  
  
  CONCLUSIONS
  An association between obstetric conditions associated with fetal hypoxia and PWR ≥90th percentile was illustrated.
  
  
  CONCLUSIONS
  The multivariable findings suggest that the PWR is similarly increased regardless of the etiology of the hypoxia.
authors.affiliation: Department of Epidemiology and Biostatistics, The University of Western Ontario, London, Canada N6A 5C1. Electronic address: emacd02@gmail.com.
authors.forename: E M
authors.initials: EM
authors.lastname: Macdonald
authors.affiliation: Department of Obstetrics and Gynecology, The University of Western Ontario, London, Canada N6A 5C1; Department of Paediatrics, The University of Western Ontario, London, Canada N6A 5C1. Electronic address: Renato.Natale@lhsc.on.ca.
authors.forename: R
authors.initials: R
authors.lastname: Natale
authors.affiliation: Department of Obstetrics and Gynecology, The University of Western Ontario, London, Canada N6A 5C1; Department of Physiology and Pharmacology, The University of Western Ontario, London, Canada N6A 5C1; The Children's Health Research Institute, London, Canada N6A 5C1. Electronic address: tim.regnault@uwo.ca.
authors.forename: T R H
authors.initials: TR
authors.lastname: Regnault
authors.affiliation: Department of Epidemiology and Biostatistics, The University of Western Ontario, London, Canada N6A 5C1. Electronic address: jkoval@uwo.ca.
authors.forename: J J
authors.initials: JJ
authors.lastname: Koval
authors.affiliation: Department of Epidemiology and Biostatistics, The University of Western Ontario, London, Canada N6A 5C1; Department of Obstetrics and Gynecology, The University of Western Ontario, London, Canada N6A 5C1; Department of Paediatrics, The University of Western Ontario, London, Canada N6A 5C1; The Children's Health Research Institute, London, Canada N6A 5C1. Electronic address: karen.campbell@schulich.uwo.ca.
authors.forename: M K
authors.initials: MK
authors.lastname: Campbell
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D047109:Fetal Development; D005311:Fetal Hypoxia / Q000209:etiology*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D009929:Organ Size; D010929:Placentation; D011247:Pregnancy; D055815:Young Adult
keywords: Fetal growth; Hypoxia; Placental growth; Placental weight ratio