Genetic and environmental factors affecting birth size variation: A pooled individual-based analysis of secular trends and global geographical differences using 26 twin cohorts

Yoshie Yokoyama*, Aline Jelenkovic, Yoon Mi Hur, Reijo Sund, Corrado Fagnani, Maria A. Stazi, Sonia Brescianini, Fuling Ji, Feng Ning, Zengchang Pang, Ariel Knafo-Noam, David Mankuta, Lior Abramson, Esther Rebato, John L. Hopper, Tessa L. Cutler, Kimberly J. Saudino, Tracy L. Nelson, Keith E. Whitfield, Robin P. CorleyBrooke M. Huibregtse, Catherine A. Derom, Robert F. Vlietinck, Ruth J.F. Loos, Clare H. Llewellyn, Abigail Fisher, Morten Bjerregaard-Andersen, Henning Beck-Nielsen, Morten Sodemann, Robert F. Krueger, Matt McGue, Shandell Pahlen, Meike Bartels, Catharina E.M. Van Beijsterveldt, Gonneke Willemsen, Jennifer R. Harris, Ingunn Brandt, Thomas S. Nilsen, Jeffrey M. Craig, Richard Saffery, Lise Dubois, Michel Boivin, Mara Brendgen, Ginette Dionne, Frank Vitaro, Claire M.A. Haworth, Robert Plomin, Gombojav Bayasgalan, Danshiitsoodol Narandalai, Finn Rasmussen, Per Tynelius, Adam D. Tarnoki, David L. Tarnoki, Syuichi Ooki, Richard J. Rose, Kirsi H. Pietiläinen, Thorkild I.A. Sørensen, Dorret I. Boomsma, Jaakko Kaprio, Karri Silventoinen

*Corresponding author for this work

Research output: Contribution to JournalArticle

Abstract

Background: The genetic architecture of birth size may differ geographically and over time. We examined differences in the genetic and environmental contributions to birthweight, length and ponderal index (PI) across geographical-cultural regions (Europe, North America and Australia, and East Asia) and across birth cohorts, and how gestational age modifies these effects. Methods: Data from 26 twin cohorts in 16 countries including 57 613 monozygotic and dizygotic twin pairs were pooled. Genetic and environmental variations of birth size were estimated using genetic structural equation modelling. Results: The variance of birthweight and length was predominantly explained by shared environmental factors, whereas the variance of PI was explained both by shared and unique environmental factors. Genetic variance contributing to birth size was small. Adjusting for gestational age decreased the proportions of shared environmental variance and increased the propositions of unique environmental variance. Genetic variance was similar in the geographical-cultural regions, but shared environmental variance was smaller in East Asia than in Europe and North America and Australia. The total variance and shared environmental variance of birth length and PI were greater from the birth cohort 1990-99 onwards compared with the birth cohorts from 1970-79 to 1980-89. Conclusions: The contribution of genetic factors to birth size is smaller than that of shared environmental factors, which is partly explained by gestational age. Shared environmental variances of birth length and PI were greater in the latest birth cohorts and differed also across geographical-cultural regions. Shared environmental factors are important when explaining differences in the variation of birth size globally and over time.

Original languageEnglish
Pages (from-to)1195-1206
Number of pages12
JournalInternational Journal of Epidemiology
Volume47
Issue number4
Early online date19 May 2018
DOIs
Publication statusPublished - 1 Aug 2018

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Keywords

  • Birth length
  • Birthweight
  • Genetics
  • Ponderal index
  • Pooled studies
  • Twins

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