International standards for newborn weight, length, and head circumference by gestational age and sex: the Newborn Cross-Sectional Study of the INTERGROWTH-21st Project

Prof José Villar MD a

, Leila Cheikh Ismail PhD a, Prof Cesar G Victora MD d, Eric O Ohuma MSc a b, Prof Enrico Bertino MD e,Prof Doug G Altman DSc b, Ann Lambert PhD a, Aris T Papageorghiou MD a, Maria Carvalho MD f, Yasmin A Jaffer MD g, Michael G Gravett MD h, Manorama Purwar MD i, Ihunnaya O Frederick PhD j, Prof Alison J Noble DPhil c, Prof Ruyan Pang MD k, ProfFernando C Barros MD d l, Prof Cameron Chumlea PhD m, Prof Zulfiqar A Bhutta PhD n o *, Stephen H Kennedy a *, for the International Fetal and Newborn Growth Consortium for the 21st Century (INTERGROWTH-21st)†

Summary

Background

In 2006, WHO published international growth standards for children younger than 5 years, which are now accepted worldwide. In the INTERGROWTH-21st 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-21st 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-21st 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.

Findings

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.

Interpretation

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.

Funding

Bill & Melinda Gates Foundation.

a Nuffield Department of Obstetrics and Gynaecology and Oxford Maternal and Perinatal Health Institute, Green Templeton College, University of Oxford, Oxford, UK

b Centre for Statistics in Medicine, Botnar Research Centre, University of Oxford, Oxford, UK

c Department of Engineering Science, University of Oxford, Oxford, UK

d Programa de Pós-Graduaçao em Epidemiologia, Universidade Federal de Pelotas, Pelotas, Brazil

e Dipartimento di Scienze Pediatriche e dell'Adolescenza, Cattedra di Neonatologia, Universita degli Studi di Torino, Torino, Italy

f Faculty of Health Sciences, Aga Khan University, Nairobi, Kenya

g Department of Family and Community Health, Ministry of Health, Muscat, Oman

h University of Washington School of Medicine, Seattle, WA, USA

i Nagpur INTERGROWTH-21st Research Centre, Ketkar Hospital, Nagpur, India

j Center for Perinatal Studies, Swedish Medical Center, Seattle, WA, USA

k School of Public Health, Peking University, Beijing, China

l Programa de Pós-Graduação em Saúde e Comportamento, Universidade Católica de Pelotas, Pelotas, Brazil

m Lifespan Health Research Center Boonshoft School of Medicine, Wright State University, Dayton, OH, USA

n Division of Women and Child Health, The Aga Khan University, Karachi, Pakistan

o Center for Global Health, Hospital for Sick Children, Toronto, ON, Canada

Correspondence to: Prof José Villar, Nuffield Department of Obstetrics and Gynaecology, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK

* Joint senior authors

† Members listed at the end of this paper