title: Diagnostic test characteristics of placental weight in the prediction of small-for-gestational-age neonates.
abstract: OBJECTIVE
  To assess the diagnostic test characteristics of placental weight as a clinical predictor of small-for-gestational-age (SGA) neonates.
  
  
  METHODS
  Placentas were weighed at 45,846 deliveries. Predictive values and likelihood ratios (LRs) were calculated assessing placental weight (lowest tertile vs. top 2 or mid/high tertiles) as a predictor of SGA both overall and by maternal age, gestational age, maternal weight, reported early pregnancy smoking, race, neonatal sex and parity.
  
  
  RESULTS
  Although the positive predictive value (PPV) of low placental weight was poor (0.19), the negative predictive value (NPV) was high (0.97). Both NPV and LR- were powerfully predictive in women at earlier gestational ages. At gestational ages <32 weeks, LR-was 0.11, showing that among women with mid/high placental weight, the proportion with SGA (false negative) was about 1/10 that without SGA (true negative).
  
  
  CONCLUSIONS
  Placental weight in the mid or upper tertile has strong NPV and LR- for delivery of an SGA neonate. Further study of the value of placental size in prediction of SGA is warranted.
authors.affiliation: Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, and Magee-Womens Research Institute, Pittsburgh, Pennsylvania 15261, USA. repro@pitt.edu
authors.forename: Roberta B
authors.initials: RB
authors.lastname: Ness
authors.forename: Debra
authors.initials: D
authors.lastname: Bass
authors.forename: Lyndon
authors.initials: L
authors.lastname: Hill
authors.forename: Mark A
authors.initials: MA
authors.lastname: Klebanoff
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
mesh_terms: D000293:Adolescent; D000328:Adult; D001837:Body Weights and Measures / Q000379:methods*; D002648:Child; D015331:Cohort Studies; D005260:Female; D005317:Fetal Growth Retardation / Q000175:diagnosis*; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D009929:Organ Size; D010920:Placenta / Q000033:anatomy & histology*; D011237:Predictive Value of Tests; D011247:Pregnancy