According to the American Psychiatric Association (APA) in the Diagnostic and Statistical Manual of Mental Disorders (amazon.com), the prevalence of MtF transsexualism is 1 in 30,000 and the prevalance of FtM transsexualism is 1 in 100,000.
From the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, page 579:
"There are no recent epidemiological studies to provide data on prevalence of Gender Identity Disorder. Data from smaller countries in Europe with access to total population statistics and referrals suggest that roughly 1 per 30,000 adult males and 1 per 100,000 adult females seek sex-reassignment surgery."
Several authorities in the field dispute the American Psychiatric Association's numbers for prevalence. In 2001, Lynn Conway, wrote an essay titled "How Frequently Does Transsexualism Occur?" in which she made the case that the prevalence of transsexualism was possibly as much as two orders of magnitude underestimated by the APA. Professor Conway used two different techniques to estimate the prevalence of transsexualism, arriving at an estimate of between 1 in 250 to 1 in 2500. In 2007, Femke Olyslager and Professor Conway performed follow-up work to systematically analyze earlier research, finding major errors in methodology.
More recently, in November 2010, the Gender Identity Research and Education Society (GIRES) in the U.K. reported on prevalence of transsexualism in the U.K, finding a current prevalence of 1 in 5000, with prevalence of 1 in 2222 in some areas. The report also found an increase in prevalence of 15 percent per year, indicating that these estimates for prevalence are likely to be low, with the increase being driven by better social, medical and legislative provisions for transgender people. These estimates agree with the numbers found by Conway and Olyslager, lending increased credence to the position that transsexualism and transgenderism are not as rare as has been previously reported.
- ↑ American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision. American Psychiatric Publishing, Inc., 2000. Print.
- ↑ "How Frequently Does Transsexualism Occur?" Lynn Conway. Lynn Conway. 2001 Web May 5, 2011
- ↑ Olyslager F, Conway L. "On the Calculation of the Prevalence of Transsexualism" WPATH 20th International Symposium. Sep 2007. Web.
- ↑ Reed B, Rhodes S, Schofield P, Wylie K. "Gender Variance in the UK: Prevalence, Incidence, Growth and Geographic Distribution." Gender Identity Research and Education Society. Jun 2009. Web.