title: International standards for newborn weight, length, and head circumference by gestational age and sex: the Newborn Cross-Sectional Study of the INTERGROWTH-21st Project.
abstract: BACKGROUND
  In 2006, WHO published international growth standards for children younger than 5 years, which are now accepted worldwide. In the INTERGROWTH-21(st) Project, our aim was to complement them by developing international standards for fetuses, newborn infants, and the postnatal growth period of preterm infants.
  
  
  METHODS
  INTERGROWTH-21(st) is a population-based project that assessed fetal growth and newborn size in eight geographically defined urban populations. These groups were selected because most of the health and nutrition needs of mothers were met, adequate antenatal care was provided, and there were no major environmental constraints on growth. As part of the Newborn Cross-Sectional Study (NCSS), a component of INTERGROWTH-21(st) Project, we measured weight, length, and head circumference in all newborn infants, in addition to collecting data prospectively for pregnancy and the perinatal period. To construct the newborn standards, we selected all pregnancies in women meeting (in addition to the underlying population characteristics) strict individual eligibility criteria for a population at low risk of impaired fetal growth (labelled the NCSS prescriptive subpopulation). Women had a reliable ultrasound estimate of gestational age using crown-rump length before 14 weeks of gestation or biparietal diameter if antenatal care started between 14 weeks and 24 weeks or less of gestation. Newborn anthropometric measures were obtained within 12 h of birth by identically trained anthropometric teams using the same equipment at all sites. Fractional polynomials assuming a skewed t distribution were used to estimate the fitted centiles.
  
  
  RESULTS
  We identified 20,486 (35%) eligible women from the 59,137 pregnant women enrolled in NCSS between May 14, 2009, and Aug 2, 2013. We calculated sex-specific observed and smoothed centiles for weight, length, and head circumference for gestational age at birth. The observed and smoothed centiles were almost identical. We present the 3rd, 10th, 50th, 90th, and 97th centile curves according to gestational age and sex.
  
  
  CONCLUSIONS
  We have developed, for routine clinical practice, international anthropometric standards to assess newborn size that are intended to complement the WHO Child Growth Standards and allow comparisons across multiethnic populations.
  
  
  BACKGROUND
  Bill & Melinda Gates Foundation.
authors.affiliation: Nuffield Department of Obstetrics and Gynaecology and Oxford Maternal and Perinatal Health Institute, Green Templeton College, University of Oxford, Oxford, UK. Electronic address: jose.villar@obs-gyn.ox.ac.uk.
authors.forename: José
authors.initials: J
authors.lastname: Villar
authors.affiliation: Nuffield Department of Obstetrics and Gynaecology and Oxford Maternal and Perinatal Health Institute, Green Templeton College, University of Oxford, Oxford, UK.
authors.forename: Leila
authors.initials: L
authors.lastname: Cheikh Ismail
authors.affiliation: Programa de Pós-Graduaçao em Epidemiologia, Universidade Federal de Pelotas, Pelotas, Brazil.
authors.forename: Cesar G
authors.initials: CG
authors.lastname: Victora
authors.affiliation: Nuffield Department of Obstetrics and Gynaecology and Oxford Maternal and Perinatal Health Institute, Green Templeton College, University of Oxford, Oxford, UK; Centre for Statistics in Medicine, Botnar Research Centre, University of Oxford, Oxford, UK.
authors.forename: Eric O
authors.initials: EO
authors.lastname: Ohuma
authors.affiliation: Dipartimento di Scienze Pediatriche e dell'Adolescenza, Cattedra di Neonatologia, Universita degli Studi di Torino, Torino, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Bertino
authors.affiliation: Centre for Statistics in Medicine, Botnar Research Centre, University of Oxford, Oxford, UK.
authors.forename: Doug G
authors.initials: DG
authors.lastname: Altman
authors.affiliation: Nuffield Department of Obstetrics and Gynaecology and Oxford Maternal and Perinatal Health Institute, Green Templeton College, University of Oxford, Oxford, UK.
authors.forename: Ann
authors.initials: A
authors.lastname: Lambert
authors.affiliation: Nuffield Department of Obstetrics and Gynaecology and Oxford Maternal and Perinatal Health Institute, Green Templeton College, University of Oxford, Oxford, UK.
authors.forename: Aris T
authors.initials: AT
authors.lastname: Papageorghiou
authors.affiliation: Faculty of Health Sciences, Aga Khan University, Nairobi, Kenya.
authors.forename: Maria
authors.initials: M
authors.lastname: Carvalho
authors.affiliation: Department of Family and Community Health, Ministry of Health, Muscat, Oman.
authors.forename: Yasmin A
authors.initials: YA
authors.lastname: Jaffer
authors.affiliation: University of Washington School of Medicine, Seattle, WA, USA.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Gravett
authors.affiliation: Nagpur INTERGROWTH-21(st) Research Centre, Ketkar Hospital, Nagpur, India.
authors.forename: Manorama
authors.initials: M
authors.lastname: Purwar
authors.affiliation: Center for Perinatal Studies, Swedish Medical Center, Seattle, WA, USA.
authors.forename: Ihunnaya O
authors.initials: IO
authors.lastname: Frederick
authors.affiliation: Department of Engineering Science, University of Oxford, Oxford, UK.
authors.forename: Alison J
authors.initials: AJ
authors.lastname: Noble
authors.affiliation: School of Public Health, Peking University, Beijing, China.
authors.forename: Ruyan
authors.initials: R
authors.lastname: Pang
authors.affiliation: Programa de Pós-Graduaçao em Epidemiologia, Universidade Federal de Pelotas, Pelotas, Brazil; Programa de Pós-Graduação em Saúde e Comportamento, Universidade Católica de Pelotas, Pelotas, Brazil.
authors.forename: Fernando C
authors.initials: FC
authors.lastname: Barros
authors.affiliation: Lifespan Health Research Center Boonshoft School of Medicine, Wright State University, Dayton, OH, USA.
authors.forename: Cameron
authors.initials: C
authors.lastname: Chumlea
authors.affiliation: Division of Women and Child Health, The Aga Khan University, Karachi, Pakistan; Center for Global Health, Hospital for Sick Children, Toronto, ON, Canada.
authors.forename: Zulfiqar A
authors.initials: ZA
authors.lastname: Bhutta
authors.affiliation: Nuffield Department of Obstetrics and Gynaecology and Oxford Maternal and Perinatal Health Institute, Green Templeton College, University of Oxford, Oxford, UK.
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Kennedy
mesh_terms: D000293:Adolescent; D000328:Adult; D000886:Anthropometry / Q000379:methods*; D001724:Birth Weight / Q000502:physiology*; D001827:Body Height / Q000502:physiology; D002508:Cephalometry / Q000592:standards; D003430:Cross-Sectional Studies; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D008297:Male; D008423:Maternal Age; D011247:Pregnancy; D011446:Prospective Studies; D012015:Reference Standards; D012727:Sex Characteristics; D055815:Young Adult