title: Changes in birth weight between 2002 and 2012 in Guangzhou, China.
abstract: BACKGROUND
  Recent surveillance data suggest that mean birth weight has begun to decline in several developed countries. The aim of this study is to examine the changes in birth weight among singleton live births from 2002 to 2012 in Guangzhou, one of the most rapidly developed cities in China.
  
  
  METHODS
  We used data from the Guangzhou Perinatal Health Care and Delivery Surveillance System for 34108 and 54575 singleton live births with 28-41 weeks of gestation, who were born to local mothers, in 2002 and 2012, respectively. The trends in birth weight, small (SGA) and large (LGA) for gestational age and gestational length were explored in the overall population and gestational age subgroups.
  
  
  RESULTS
  The mean birth weight decreased from 3162 g in 2002 to 3137 g in 2012 (crude mean difference, -25 g; 95% CI, -30 to -19). The adjusted change in mean birth weight appeared to be slight (-6 g from 2002 to 2012) after controlling for maternal age, gestational age, educational level, parity, newborn's gender and delivery mode. The percentages of SGA and LGA in 2012 were 0.6% and 1.5% lower than those in 2002, respectively. The mean gestational age dropped from 39.2 weeks in 2002 to 38.9 weeks in 2012. In the stratified analysis, we observed the changes in birth weight differed among gestational age groups. The mean birth weight decreased among very preterm births (28-31 weeks), while remained relatively stable among other gestational age subcategories.
  
  
  CONCLUSIONS
  Among local population in Guangzhou from 2002 to 2012, birth weight appeared to slightly decrease. The percentage of SGA and LGA also simultaneously dropped, indicating that newborns might gain a healthier weight for gestational age.
authors.affiliation: 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.forename: Yong
authors.initials: Y
authors.lastname: Guo
authors.affiliation: 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.forename: Yu
authors.initials: Y
authors.lastname: Liu
authors.affiliation: 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.forename: Jian-Rong
authors.initials: JR
authors.lastname: He
authors.affiliation: 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; Guangzhou Women and Children's Health Information Center, Guangzhou, China.
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Xia
authors.affiliation: Department of Health Care, Guangzhou Women and Children's Medical Center, Guangzhou, China.
authors.forename: Wei-Jian
authors.initials: WJ
authors.lastname: Mo
authors.affiliation: Department of Health Care, Guangzhou Women and Children's Medical Center, Guangzhou, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.affiliation: Department of Health Care, Guangzhou Women and Children's Medical Center, Guangzhou, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Feng
authors.affiliation: Centre for International Child Health, BC Children's Hospital and University of British Columbia, Vancouver, Canada.
authors.forename: Charles P
authors.initials: CP
authors.lastname: Larson
authors.affiliation: Division of Birth Cohort Study, Guangzhou Women and Children's Medical Center, Guangzhou, China.
authors.forename: Hui-Min
authors.initials: HM
authors.lastname: Xia
authors.affiliation: 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.forename: Xiu
authors.initials: X
authors.lastname: Qiu
mesh_terms: D000328:Adult; D001724:Birth Weight; D002681:China; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D050498:Live Birth; D008297:Male; D008423:Maternal Age; D010298:Parity; D011247:Pregnancy; D047928:Premature Birth; D013997:Time Factors