title: Association of placental weight with cerebral palsy: population-based cohort study in Norway.
abstract: To study the risk of cerebral palsy (CP) associated with placental weight, and also with placental weight/birthweight ratio and placental weight/birth length ratio.
  
  
  
  Population-based cohort study.
  
  
  
  Perinatal data in the Medical Birth Registry of Norway were linked with clinical data in the CP Register of Norway.
  
  
  
  A total of 533 743 singleton liveborn children in Norway during 1999-2008. Of these, 779 children were diagnosed with CP.
  
  
  
  Placental weight, placental weight/birthweight ratio, and placental weight/birth length ratio were grouped into gestational age-specific quartiles. Odds ratios (OR) with 95% confidence intervals (95% CI) for CP were calculated for children with exposure variables in the lowest or in the highest quartile, using the second to third quartile as the reference.
  
  
  
  CP and CP subtypes.
  
  
  
  Overall, children with low placental weight had increased risk for CP (OR 1.5, 95% CI 1.2-1.7). Low placental weight/birthweight ratio (OR 1.2, 95% CI 1.0-1.4) and low placental weight/birth length ratio (OR 1.5, 95% CI 1.2-1.8) were also associated with increased risk for CP. In children born at term, low placental weight was associated with a twofold increase in risk for spastic bilateral CP (including both quadriplegia and diplegia) (OR 2.1, 95% CI 1.5-2.9). In children born preterm, high placental ratios were associated with increased risk for spastic quadriplegia.
  
  
  
  Our results suggest that placental dysfunction may be involved in causal pathways leading to the more severe subtypes of CP.
  
  
  
  Low placental weight increases the risk for cerebral palsy, especially for the spastic bilateral subtype.
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: K M
authors.initials: KM
authors.lastname: Strand
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.|The Cerebral Palsy Register of Norway, Habilitation Centre, Vestfold Hospital Trust, Tønsberg, Norway.
authors.forename: G L
authors.initials: GL
authors.lastname: Andersen
authors.affiliation: Department of Obstetrics and Gynecology, Akershus University Hospital, Lørenskog, Norway.
authors.forename: C
authors.initials: C
authors.lastname: Haavaldsen
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: T
authors.initials: T
authors.lastname: Vik
authors.affiliation: Department of Obstetrics and Gynecology, Akershus University Hospital, Lørenskog, Norway.|Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
authors.forename: A
authors.initials: A
authors.lastname: Eskild
mesh_terms: D001034:Apgar Score; D001724:Birth Weight; D002547:Cerebral Palsy / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology; D015331:Cohort Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D008297:Male; D009664:Norway / Q000453:epidemiology; D009929:Organ Size; D010920:Placenta / Q000473:pathology / Q000503:physiopathology; D011247:Pregnancy; D012042:Registries / Q000706:statistics & numerical data; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D012720:Severity of Illness Index; D013223:Statistics as Topic
keywords: Birthweight; epidemiology; placenta; pregnancy; risk factors