title: Prevalence of small-for-gestational-age and its mortality risk varies by choice of birth-weight-for-gestation reference population.
abstract: BACKGROUND
  We use data from rural Nepal and South India to compare the prevalence of small-for-gestational-age (SGA) and neonatal mortality risk associated with SGA using different birth-weight-for-gestation reference populations.
  
  
  METHODS
  We identified 46 reference populations in low-, middle-, and high-income countries, of which 26 met the inclusion criteria of being commonly cited and having numeric 10th percentile cut points published. Those reference populations were then applied to populations from two community-based studies to determine SGA prevalence and its relative risk of neonatal mortality.
  
  
  RESULTS
  The prevalence of SGA ranged from 10.5% to 72.5% in Nepal, and 12.0% to 78.4% in India, depending on the reference population. Females had higher rates of SGA than males using reference populations that were not sex specific. SGA prevalence was lowest when using reference populations from low-income countries. Infants who were both preterm and SGA had much higher mortality risk than those who were term and appropriate-for-gestational-age. Risk ratios for those who are both preterm and SGA ranged from 7.34-17.98 in Nepal and 5.29-11.98 in India, depending on the reference population.
  
  
  CONCLUSIONS
  These results demonstrate the value of a common birth-weight-for-gestation reference population that will facilitate comparisons of SGA prevalence and mortality risk across research studies.
authors.affiliation: Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Joanne
authors.initials: J
authors.lastname: Katz
authors.affiliation: Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Wu
authors.affiliation: Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Luke C
authors.initials: LC
authors.lastname: Mullany
authors.affiliation: Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Christian L
authors.initials: CL
authors.lastname: Coles
authors.affiliation: Department of Newborn Medicine, Brigham and Women's Hospital, Boston, Massachusetts, United States of America.
authors.forename: Anne C C
authors.initials: AC
authors.lastname: Lee
authors.affiliation: Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Naoko
authors.initials: N
authors.lastname: Kozuki
authors.affiliation: Department of Global Health, George Washington University, School of Public Health and Health Services, Washington, DC, United States of America.
authors.forename: James M
authors.initials: JM
authors.lastname: Tielsch
mesh_terms: D001724:Birth Weight; D005260:Female; D005865:Gestational Age; D006801:Humans; D007182:Income; D007194:India / Q000453:epidemiology; D007223:Infant; D007226:Infant Mortality / Q000208:ethnology*; D007231:Infant, Newborn; D007234:Infant, Premature; D007236:Infant, Small for Gestational Age; D008297:Male; D009390:Nepal / Q000453:epidemiology; D015995:Prevalence; D012016:Reference Values; D012306:Risk; D012424:Rural Population; D012737:Sex Factors