Archives of Sexual Behavior

, Volume 39, Issue 1, pp 117–123 | Cite as

Body Size at Birth and Same-Sex Marriage in Young Adulthood

  • Morten Frisch
  • Slobodan Zdravkovic
Original Paper


An unexplained excess of overweight has been reported among lesbians. In contrast, reports suggest that gay men may be, on average, slightly lighter and shorter than heterosexual men. We studied associations between weight, length, and body mass index (BMI) at birth and same-sex marriage in young adulthood among 818,671 Danes. We used linear regression to calculate differences in mean body measures at birth and Poisson regression analysis to calculate confounder-adjusted incidence rate ratios (IRR) of same-sex marriage according to body measures at birth. Overall, 739 persons entered same-sex marriage at age 18–32 years during 5.6 million person-years of follow-up. Birth year-adjusted mean body measures at birth were similar for same-sex married and other women. However, same-sex marriage rates were 65% higher among women of heavy birth weight (IRR = 1.65; 95% CI = 1.18–2.31, for ≥4000 vs. 3000–3499 g, p = .02), and rates were inversely associated with birth length (p trend = .04). For same-sex married men, birth year-adjusted mean weight (−72 g, p = .03), length (−0.3 cm, p = .04), and BMI (−0.1 kg/m2, p = .09) at birth were lower than for other Danish men. Same-sex marriage rates were increased in men of short birth length (IRR = 1.45; 95% CI = 1.01–2.08, for ≤50 vs. 51–52 cm), although not uniformly so (p trend = .16). Our population-based findings suggest that overweight in lesbians may be partly rooted in constitutional factors. Novel findings of smaller average body measures at birth in same-sex marrying men need replication. Factors affecting intrauterine growth may somehow influence sexual and partner-related choices in adulthood.


Epidemiology Cohort studies Birth weight Body size Obesity Homosexuality 


  1. Anonymous. (1989). Act No. 372 of 7 June 1989 on registered partnerships. Annual Review of Population Law, 16, 56.Google Scholar
  2. Barker, D. J., Gluckman, P. D., Godfrey, K. M., Harding, J. E., Owens, J. A., & Robinson, J. S. (1993). Fetal nutrition and cardiovascular disease in adult life. Lancet, 341, 938–941.CrossRefPubMedGoogle Scholar
  3. Blanchard, R., & Bogaert, A. F. (1996). Biodemographic comparisons of homosexual and heterosexual men in the Kinsey Interview Data. Archives of Sexual Behavior, 25, 551–579.CrossRefPubMedGoogle Scholar
  4. Blanchard, R., Dickey, R., & Jones, C. L. (1995). Comparison of height and weight in homosexual versus nonhomosexual male gender dysphorics. Archives of Sexual Behavior, 24, 543–554.CrossRefPubMedGoogle Scholar
  5. Blanchard, R., & Ellis, L. (2001). Birth weight, sexual orientation and the sex of preceding siblings. Journal of Biosocial Science, 33, 451–467.CrossRefPubMedGoogle Scholar
  6. Blanchard, R., Zucker, K. J., Cavacas, A., Allin, S., Bradley, S. J., & Schachter, D. C. (2002). Fraternal birth order and birth weight in probably prehomosexual feminine boys. Hormones and Behavior, 41, 321–327.CrossRefPubMedGoogle Scholar
  7. Boehmer, U., Bowen, D. J., & Bauer, G. R. (2007). Overweight and obesity in sexual-minority women: Evidence from population-based data. American Journal of Public Health, 97, 1134–1140.CrossRefPubMedGoogle Scholar
  8. Bogaert, A. F. (2003). The interaction of fraternal birth order and body size in male sexual orientation. Behavioral Neuroscience, 117, 381–384.CrossRefPubMedGoogle Scholar
  9. Bogaert, A. F., & Friesen, C. (2002). Sexual orientation and height, weight, and age of puberty: New tests from a British national probability sample. Biological Psychology, 59, 135–145.CrossRefPubMedGoogle Scholar
  10. Case, P., Austin, S. B., Hunter, D. J., Manson, J. E., Malspeis, S., Willett, W. C., et al. (2004). Sexual orientation, health risk factors, and physical functioning in the Nurses’ Health Study II. Journal of Women’s Health, 13, 1033–1047.CrossRefPubMedGoogle Scholar
  11. Danish Ministry of Interior Affairs and Health. (2008). The Civil Registration System in Denmark.
  12. Frisch, M., & Hviid, A. (2006). Childhood family correlates of heterosexual and homosexual marriages: A national cohort study of two million Danes. Archives of Sexual Behavior, 35, 533–547.CrossRefPubMedGoogle Scholar
  13. Frisch, M., & Hviid, A. (2007). Reply to Blanchard’s (2007) “Older-Sibling and Younger-Sibling Sex Ratios in Frisch and Hviid’s (2006) National Cohort Study of Two Million Danes”. Archives of Sexual Behavior, 36, 864–867.CrossRefGoogle Scholar
  14. Frisch, M., Smith, E., Grulich, A., & Johansen, C. (2003). Cancer in a population-based cohort of men and women in registered homosexual partnerships. American Journal of Epidemiology, 157, 966.CrossRefPubMedGoogle Scholar
  15. Kipke, M. D., Kubicek, K., Weiss, G., Wong, C., Lopez, D., Iverson, E., et al. (2007). The health and health behaviors of young men who have sex with men. Journal of Adolescent Health, 40, 342–350.CrossRefPubMedGoogle Scholar
  16. Knudsen, L. B., & Olsen, J. (1998). The Danish Medical Birth Registry. Danish Medical Bulletin, 45, 320–323.PubMedGoogle Scholar
  17. Odlind, V., Haglund, B., Pakkanen, M., & Otterblad Olausson, P. (2003). Deliveries, mothers and newborn infants in Sweden, 1973–2000. Trends in obstetrics as reported to the Swedish Medical Birth Register. Acta Obstetricia et Gynecologica Scandinavica, 82, 516–528.PubMedGoogle Scholar
  18. Ong, K. K. (2006). Size at birth, postnatal growth and risk of obesity. Hormone Research, 65(Suppl. 3), 65–69.Google Scholar
  19. Phillips, D. I., Handelsman, D. J., Eriksson, J. G., Forsen, T., Osmond, C., & Barker, D. J. (2001). Prenatal growth and subsequent marital status: Longitudinal study. British Medical Journal, 322, 771.CrossRefPubMedGoogle Scholar
  20. Rogers, I. (2003). The influence of birthweight and intrauterine environment on adiposity and fat distribution in later life. International Journal of Obesity, 27, 755–777.CrossRefPubMedGoogle Scholar
  21. Schack-Nielsen, L., Mølgaard, C., Sørensen, T. I. A., Greisen, G., & Michaelsen, K. F. (2006). Secular change in size at birth from 1973 to 2003: National data from Denmark. Obesity, 14, 1257–1263.CrossRefPubMedGoogle Scholar
  22. Skjaerven, R., Gjessing, H. K., & Bakketeig, L. (2000). Birthweight by gestational age in Norway. Acta Obstetricia et Gynecologica Scandinavica, 79, 440–449.CrossRefPubMedGoogle Scholar
  23. Vågerö, D., & Modin, B. (2002). Prenatal growth, subsequent marital status, and mortality: Longitudinal study. British Medical Journal, 324, 398.CrossRefPubMedGoogle Scholar
  24. Valanis, B. G., Bowen, D. J., Bassford, T., Whitlock, E., Charney, P., & Carter, R. A. (2000). Sexual orientation and health: Comparisons in the Women’s Health Initiative Sample. Archives of Family Medicine, 9, 843–853.CrossRefPubMedGoogle Scholar
  25. Wen, S. W., Kramer, M. S., Platt, R., Demissie, K., Joseph, K. S., Liu, S., et al. (2003). Secular trends of fetal growth in Canada, 1981 to 1997. Pediatric and Perinatal Epidemiology, 17, 347–354.CrossRefPubMedGoogle Scholar
  26. Whitaker, R. C., & Dietz, W. H. (1998). Role of the prenatal environment in the development of obesity. Journal of Pediatrics, 132, 768–776.CrossRefPubMedGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  1. 1.Department of Epidemiology ResearchStatens Serum InstitutCopenhagen SDenmark

Personalised recommendations