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Original article
Updated birth weight centiles for England and Wales
  1. Tom Norris1,
  2. Sarah E Seaton1,
  3. Brad N Manktelow1,
  4. Philip N Baker2,
  5. Jennifer J Kurinczuk3,
  6. David Field1,
  7. Elizabeth S Draper1,
  8. Lucy K Smith4
  1. 1 Department of Health Sciences, University of Leicester, Leicester, UK
  2. 2 College of Medicine, Biological Sciences and Psychology, University of Leicester, Leicester, UK
  3. 3 National Perinatal Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK
  4. 4 Department of Health Sciences, The Infant Mortality and Morbidity Studies, Centre for Medicine, University of Leicester, Leicester, UK
  1. Correspondence to Dr Tom Norris, Department of Health Sciences, University of Leicester, Leicester LE1 7RH, UK; tom.norris{at}le.ac.uk

Abstract

Objectives Construct updated birth weight-for-gestational age centile charts for use in the UK and compare these to the currently used UK-WHO charts.

Design Secondary analysis of national birth data.

Participants Centiles were constructed using 1 269 403 singleton births occurring in England and Wales in 2013–2014 as part of the MBRRACE-UK national perinatal surveillance programme. These were then validated using 642 737 singleton births occurring in England and Wales in 2015.

Main outcome measures Sex-specific birth weight-for-gestational age centiles. Centiles were created using the lambda-mu-sigma method via the GAMLSS package in R. This method transforms the skewed birth weight distribution to approximate a normal distribution, allowing any birth weight centile to be produced.

Results The new centiles performed well in the validation sample, with the observed and expected proportion of births below a given centile in agreement. Overall, driven by the predominance of term births, the UK-WHO charts classify a smaller proportion of infants as below a given centile. For example, the UK-WHO estimates classified only 1.32% (8035/606 430) of term infants born in 2015 as below the second centile, compared with 1.97% (11 975/606 430) using the new MBRRACE-UK centiles. At the earliest gestational ages, however, the opposite is observed, with the UK-WHO classifying a larger proportion of infants as below a given centile, particularly at the lower end of the birthweight distribution.

Conclusions We have constructed and validated updated birth weight-for-gestational age centiles using a contemporary sample of births occurring in England and Wales. The benefits of these updated centiles will be first to assist the national surveillance of perinatal mortality programme by improving the identification of the proportion of stillbirths and neonatal deaths affected by intrauterine growth restriction and, second, to aid clinicians by more accurately identifying babies who require increased monitoring in the period immediately following birth.

  • birth weight
  • gestational age
  • charts
  • UK-WHO

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

https://doi.org/10.1136/archdischild-2017-313452

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    Footnotes

    • Contributors SES, BNM, DF, ESD and LKS conceived the study, provided intellectual input, interpreted the results and helped revise the manuscript. TN performed the analysis and drafted the initial version of the manuscript. PNB and JJK provided intellectual input, interpreted the results and helped revise the manuscript. All authors approved the final version of the manuscript and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; internally peer reviewed.