Original Research ARTICLE

Front. Genet., 18 July 2012 | http://dx.doi.org/10.3389/fgene.2012.00125

Assortative marriages by body mass index have increased simultaneously with the obesity epidemic

Teresa A. Ajslev1*, Lars Ängquist1†, Karri Silventoinen2, Michael Gamborg1, David B. Allison3, Jennifer L. Baker1 and Thorkild I. A. Sørensen1
  • 1Institute of Preventive Medicine, Copenhagen University Hospital, Copenhagen, Denmark
  • 2Population Research Unit, Department of Social Research, University of Helsinki, Helsinki, Finland
  • 3Nutrition Obesity Research Center, University of Alabama at Birmingham, AL, USA

Background: The genetic predisposition to obesity may have contributed to the obesity epidemic through assortative mating. We investigated whether spouses were positively assorted by body mass index (BMI; = kg/m2) in late childhood, and whether changes in assorted marriage by upper BMI-percentiles occurred during the obesity epidemic. Methods: In the Copenhagen School Health Records Register (CSHRR) boys and girls with measures of BMI at age 13 years later became 37,792 spousal-pairs who married between 1945 and 2010. Trends in the spousal BMI correlations using sex-, age-, and birth cohort-specific BMI z-scores across time were investigated. Odds ratios (ORs) of marriage among spouses both with BMI z-scores >90th or >95th percentile compared with marriage among spouses ≤90th percentile were analyzed for marriages entered during the years prior to (1945–1970), and during the obesity epidemic (1971–2010). Findings: Spousal BMI correlations were around 0.05 and stayed similar across time. ORs of marriage among spouses with BMIs >90th percentile at age 13 were 1.21, 1.05–1.39, in 1945–1970, and increased to 1.63, 1.40–1.91, in 1971–2010 (p = 0.006). ORs of marriage among spouses both >95th BMI percentile were higher and increased more; from 1.39, 1.10–1.81, to 2.39, 1.85–3.09 (p = 0.004). Interpretation: Spousal correlations by pre-marital BMIs were small and stable during the past 65 years. Yet, there were assorted marriages between spouses with high BMI at age 13 years and the tendency increased alongside with the obesity epidemic which may increase the offsprings' predisposition to obesity.

Keywords: assortative mating, body mass index, childhood, obesity, overweight, phenotype, human genetics

Citation: Ajslev TA, Ängquist L, Silventoinen K, Gamborg M, Allison DB, Baker JL and Sørensen TIA (2012) Assortative marriages by body mass index have increased simultaneously with the obesity epidemic. Front. Gene. 3:125. doi: 10.3389/fgene.2012.00125

Received: 16 March 2012; Accepted: 21 June 2012;
Published online: 18 July 2012.

Edited by:

Paul Franks, Lund University, Sweden

Reviewed by:

Lijun Ma, Wake Forest University Health Sciences, USA
Frida Renstrom, Lund University, Sweden
Lawrence De Koning, McMaster University, Canada

Copyright © 2012 Ajslev, Ängquist, Silventoinen, Gamborg, Allison, Baker and Sørensen. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.

*Correspondence: Teresa A. Ajslev, Institute of Preventive Medicine, Copenhagen University Hospital, Nordre Fasanvej 57, DK- 2000 Frederiksberg, Denmark. e-mail: ta@ipm.regionh.dk

Shared first authorship.