title: External Validation of Early Weight Loss Nomograms for Exclusively Breastfed Newborns.
abstract: BACKGROUND
  Nomograms that show hour-by-hour percentiles of weight loss during the birth hospitalization were recently developed to aid clinical care of breastfeeding newborns. The nomograms for breastfed neonates were based on a sample of 108,907 newborns delivered at 14 Kaiser Permanente medical centers in Northern California (United States). The objective of this study was to externally validate the published nomograms for newborn weight loss using data from a geographically distinct population.
  
  
  METHODS
  Data were compiled from the Penn State Milton S. Hershey Medical Center located in Hershey, PA. For singleton neonates delivered at ≥36 weeks of gestation between January 2013 and September 2014, weights were obtained between 6 hours and 48 hours (vaginal delivery) or 60 hours (cesarean delivery) for neonates who were exclusively breastfeeding. Quantile regression methods appropriate for repeated measures were used to estimate 50th, 75th, 90th, and 95th percentiles of weight loss as a function of time after birth. These percentile estimates were compared with the published nomograms.
  
  
  RESULTS
  Of the 1,587 newborns who met inclusion criteria, 1,148 were delivered vaginally, and 439 were delivered via cesarean section. These newborns contributed 1,815 weights for vaginal deliveries (1.6 per newborn) and 893 weights for cesarean deliveries (2.0 per newborn). Percentile estimates from this Penn State sample were similar to the published nomograms. Deviations in percentile estimates for the Penn State sample were similar to deviations observed after fitting the same model separately to each medical center that made up the Kaiser Permanente sample.
  
  
  CONCLUSIONS
  The published newborn weight loss nomograms for breastfed neonates were externally validated in a geographically distinct population.
authors.affiliation: 1 Department of Public Health Sciences, Penn State College of Medicine , Hershey, Pennsylvania.
authors.forename: Eric W
authors.initials: EW
authors.lastname: Schaefer
authors.affiliation: 2 Department of Pediatrics, School of Medicine, University of California , San Francisco, California.|3 Department of Epidemiology and Biostatistics, School of Medicine, University of California , San Francisco, California.
authors.forename: Valerie J
authors.initials: VJ
authors.lastname: Flaherman
authors.affiliation: 2 Department of Pediatrics, School of Medicine, University of California , San Francisco, California.|4 Division of Research, Kaiser Permanente Northern California , Oakland, California.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Kuzniewicz
authors.affiliation: 4 Division of Research, Kaiser Permanente Northern California , Oakland, California.
authors.forename: Sherian X
authors.initials: SX
authors.lastname: Li
authors.affiliation: 4 Division of Research, Kaiser Permanente Northern California , Oakland, California.
authors.forename: Eileen M
authors.initials: EM
authors.lastname: Walsh
authors.affiliation: 1 Department of Public Health Sciences, Penn State College of Medicine , Hershey, Pennsylvania.|5 Department of Pediatrics, Penn State College of Medicine , Hershey, Pennsylvania.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Paul
mesh_terms: D000367:Age Factors; D001724:Birth Weight; D001942:Breast Feeding / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D049451:Nomograms; D011247:Pregnancy; D014481:United States / Q000453:epidemiology; D015431:Weight Loss