Twin's Birth-Order Differences in Height and Body Mass Index from Birth to Old Age: A Pooled Study of 26 Twin Cohorts Participating in the CODATwins Project

Yoshie Yokoyama*, Aline Jelenkovic, Reijo Sund, Joohon Sung, John L. Hopper, Syuichi Ooki, Kauko Heikkilä, Sari Aaltonen, Adam D. Tarnoki, David L. Tarnoki, Gonneke Willemsen, Meike Bartels, Toos C.E.M. Van Beijsterveldt, Kimberly J. Saudino, Tessa L. Cutler, Tracy L. Nelson, Keith E. Whitfield, Jane Wardle, Clare H. Llewellyn, Abigail FisherMingguang He, Xiaohu Ding, Morten Bjerregaard-Andersen, Henning Beck-Nielsen, Morten Sodemann, Yun Mi Song, Sarah Yang, Kayoung Lee, Hoe Uk Jeong, Ariel Knafo-Noam, David Mankuta, Lior Abramson, S. Alexandra Burt, Kelly L. Klump, Juan R. Ordoñana, Juan F. Sánchez-Romera, Lucia Colodro-Conde, Jennifer R. Harris, Ingunn Brandt, Thomas Sevenius Nilsen, Jeffrey M. Craig, Richard Saffery, Fuling Ji, Feng Ning, Zengchang Pang, Lise Dubois, Michel Boivin, Mara Brendgen, Ginette Dionne, Frank Vitaro, Nicholas G. Martin, Sarah E. Medland, Grant W. Montgomery, Patrik K.E. Magnusson, Nancy L. Pedersen, Anna K.Dahl Aslan, Per Tynelius, Claire M.A. Haworth, Robert Plomin, Esther Rebato, Richard J. Rose, Jack H. Goldberg, Finn Rasmussen, Yoon Mi Hur, Thorkild I.A. Sørensen, Dorret I. Boomsma, Jaakko Kaprio, Karri Silventoinen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


We analyzed birth order differences in means and variances of height and body mass index (BMI) in monozygotic (MZ) and dizygotic (DZ) twins from infancy to old age. The data were derived from the international CODATwins database. The total number of height and BMI measures from 0.5 to 79.5 years of age was 397,466. As expected, first-born twins had greater birth weight than second-born twins. With respect to height, first-born twins were slightly taller than second-born twins in childhood. After adjusting the results for birth weight, the birth order differences decreased and were no longer statistically significant. First-born twins had greater BMI than the second-born twins over childhood and adolescence. After adjusting the results for birth weight, birth order was still associated with BMI until 12 years of age. No interaction effect between birth order and zygosity was found. Only limited evidence was found that birth order influenced variances of height or BMI. The results were similar among boys and girls and also in MZ and DZ twins. Overall, the differences in height and BMI between first- and second-born twins were modest even in early childhood, while adjustment for birth weight reduced the birth order differences but did not remove them for BMI.

Original languageAmerican English
Pages (from-to)112-124
Number of pages13
JournalTwin Research and Human Genetics
Issue number2
StatePublished - 1 Apr 2016

Bibliographical note

Publisher Copyright:
© The Author(s) 2016.


  • BMI
  • birth order
  • height
  • zygosity


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