title: A new birthweight reference in Guangzhou, southern China, and its comparison with the global reference.
abstract: OBJECTIVE
  To formulate a new birthweight reference for different gestational ages in Guangzhou, southern China, and compare it with the currently used reference in China and the global reference.
  
  
  METHODS
  All singleton live births of more than 26 weeks' gestational age recorded in the Guangzhou Perinatal Health Care and Delivery Surveillance System for the years 2009, 2010 and 2011 (n=510 837) were retrospectively included in the study. In addition, the study sample was supplemented by all singleton live births (n=3538) at gestational ages 26-33 weeks from 2007 and 2008. We used Gaussian mixture models and robust regression to exclude outliers of birth weight and then applied Generalized Additive Models for Location, Scale, and Shape (GAMLSS) to generate smoothed percentile curves separately for gender and parity.
  
  
  RESULTS
  Of infants defined as small for gestational age (SGA) in the new reference, 15.3-47.7% (depending on gestational age) were considered appropriate for gestational age (AGA) by the currently used reference of China. Of the infants defined as SGA by the new reference, 9.2% with gestational ages 34-36 weeks and 14.3% with 37-41 weeks were considered AGA by the global reference. At the 50th centile line, the new reference curve was similar to that of the global reference for gestational ages 26-33 weeks and above the global reference for 34-40 weeks.
  
  
  CONCLUSIONS
  The new birthweight reference based on birthweight data for neonates in Guangzhou, China, differs from the reference currently used in China and the global reference, and appears to be more relevant to the local population.
authors: Division of Birth Cohort Study, Guangzhou Women and Children's Medical Center, Guangzhou, China Department of Health Care, Guangzhou Women and Children's Medical Center, Guangzhou, China.
authors: Jian-Rong
authors: JR
authors: He
authors: Division of Birth Cohort Study, Guangzhou Women and Children's Medical Center, Guangzhou, China.
authors: Hui-Min
authors: HM
authors: Xia
authors: Division of Birth Cohort Study, Guangzhou Women and Children's Medical Center, Guangzhou, China Department of Health Care, Guangzhou Women and Children's Medical Center, Guangzhou, China.
authors: Yu
authors: Y
authors: Liu
authors: Division of Birth Cohort Study, Guangzhou Women and Children's Medical Center, Guangzhou, China Department of Health Care, Guangzhou Women and Children's Medical Center, Guangzhou, China.
authors: Xiao-Yan
authors: XY
authors: Xia
authors: Department of Health Care, Guangzhou Women and Children's Medical Center, Guangzhou, China.
authors: Wei-Jian
authors: WJ
authors: Mo
authors: Department of Health Care, Guangzhou Women and Children's Medical Center, Guangzhou, China.
authors: Ping
authors: P
authors: Wang
authors: Department of Public Health and Epidemiology, University of Birmingham, Birmingham, UK.
authors: Kar Keung
authors: KK
authors: Cheng
authors: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, China.
authors: Gabriel M
authors: GM
authors: Leung
authors: Department of Health Care, Guangzhou Women and Children's Medical Center, Guangzhou, China.
authors: Qiong
authors: Q
authors: Feng
authors: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, SAR, China CUNY School of Public Health at Hunter College, New York, New York, USA.
authors: C Mary
authors: CM
authors: Schooling
authors: Division of Birth Cohort Study, Guangzhou Women and Children's Medical Center, Guangzhou, China Department of Health Care, Guangzhou Women and Children's Medical Center, Guangzhou, China.
authors: Xiu
authors: X
authors: Qiu
mesh_terms: D001724:Birth Weight; D002681:China; D005260:Female; D005865:Gestational Age; D014943:Global Health; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D008297:Male; D011247:Pregnancy; D012016:Reference Values; D012189:Retrospective Studies
keywords: Epidemiology; Fetal Medicine; Growth