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An updated reference for age-sex-specific birth weight percentiles stratified for ethnicity based on data from all live birth infants between 2005 and 2014 in Alberta, Canada



This study aims to update the current reference for sex-specific birth weight percentiles by gestational age, overall and for specific ethnic groups, based on data from all singleton live-birth deliveries from 2005 to 2014 in Alberta, Canada.


Infant and maternal information were captured in the Alberta Vital Statistics-Births Database for 473,115 singleton infants born to 311,800 women between January 1, 2005 and December 31, 2014. Within each sex, and each sex-ethnic group, birth weights were modelled by gestational age using generalized additive models and natural cubic splines. Crude and corrected estimates for birth weight percentiles including cut-off values for large for gestational age (LGA) and small for gestational age (SGA) were calculated by sex and sex-ethnic group, and gestational age for singleton live births.


LGA and SGA cut-offs were lower for females than for males for all gestational ages. The SGA and LGA percentiles were greater for both male and female very preterm infants in Alberta compared to previous national references. Ethnicity-specific LGA and SGA cut-offs for term Chinese and preterm and at-term South Asian infants were consistently lower than those for both the general population in Alberta and the previous national reference. South Asian infants had lower birth weights at almost all gestational ages compared with the other groups.


The updated birth weight percentiles presented in this study highlight the differences in SGA and LGA cut-offs among infants from South Asian, Chinese, and the general population, which may be important for clinical perinatal care.



L’objectif de cette étude est d’actualiser la référence actuelle pour les percentiles de poids à la naissance spécifique au sexe par l’âge gestationnel, globalement et pour des groupes ethniques spécifiques, basé sur les données de tous les accouchements de naissances vivante uniques entre 2005 et 2014 en Alberta, au Canada.


L’information infantile et maternelle ont été capturées dans les statistiques de l’état civil – base de données sur les naissances, en Alberta, pour 473 115 nourrissons uniques nés de 311 800 femmes entre le 1er janvier 2005 et le 31 décembre 2014. Dans chaque sexe, et dans chaque groupe sexe-ethnique, les poids de naissances ont été modélisés par l’âge gestationnel grâce à l’utilisation de modèles additifs généralisés et de splines cubiques naturelles. Des estimations grossières et corrigées pour les percentiles de poids à la naissance, y compris les valeurs seuils pours les nourrissons gros pour l’âge gestationnel (GAG) et petits pour l’âge gestationnel (PAG), ont été calculées par sexe et groupe sexe-ethnique, et par l’âge gestationnel pour les naissances vivantes uniques.


Les critères pour GAG et PAG étaient plus bas pour les femelles que pour les mâles pour tous les âges gestationnels. Les percentiles pour PAG et GAG étaient plus élevés pour les nourrissons mâles et femelles nés très prématurés en Alberta en comparaison avec les références nationales précédentes. Les critères pour GAG et PAG spécifiques à l’ethnicité chinoise, pour les nourrissons nés à termes, et sud-asiatiques, pour les nourrissons nés avant et à termes, étaient régulièrement plus basses que ceux de la population générale en Alberta et de la référence nationale précédente. Les nourrissons sud-asiatiques avaient des poids de naissances plus basses à presque tous les âges gestationnels en comparaison avec les autres groupes.


Les percentiles de poids à la naissance actualisés présentés dans cette étude mettent en évidence les différences de PAG et GAG entre les nourrissons sud-asiatiques, chinoises et de la population générale, qui peuvent êtres importantes pour les soins cliniques périnatales.

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The results of this study were presented at the Eighth Annual Canadian Statistics Student Conference as an oral presentation. This study is based in part on data provided by Alberta Health and Alberta Health Services. We thank the Customer Relationship Management and Data Access Unit at Alberta Health for creating the linked database. The authors appreciate the editorial assistance of colleagues in the Canadian VIGOUR Centre.

Dr. Kaul is a Canadian Institutes of Health Research Chair in Sex and Gender Science and is supported by the Heart & Stroke Chair in Cardiovascular Research.

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This study was funded by the Canadian Institutes of Health Research (#377645).

Author information




PK conceived of the presented idea. AS, LM, and MH developed the theory and performed the computations. ID verified the analytical methods. All the authors discussed the results and contributed to the final manuscript.

Corresponding author

Correspondence to Padma Kaul.

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Ethics approval

This study was approved by the University of Alberta Research Ethics Board (Pro00056999).

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The ethics panel determined that the research is a retrospective database review for which subject consent for access to personally identifiable health information would not be reasonable, feasible, or practical.

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Not applicable.

Conflict of interest

The authors report they have no competing interests.

Data statement

The authors had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. The interpretation and conclusions contained herein are those of the researchers and do not necessarily represent the views of the Government of Alberta. Neither the Government nor Alberta Health express any opinion in relation to this study.

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Hajihosseini, M., Savu, A., Moore, L. et al. An updated reference for age-sex-specific birth weight percentiles stratified for ethnicity based on data from all live birth infants between 2005 and 2014 in Alberta, Canada. Can J Public Health (2021).

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  • Birth weight
  • Gestational age
  • Ethnicity
  • Live birth
  • Canada


  • Poids à la naissance
  • âge gestationnel
  • ethnicité
  • naissance vivante
  • Canada