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ORIGINAL RESEARCH—LGBT
Evidence for an Altered Sex Ratio in Clinic-Referred Adolescents
with Gender Dysphoria
Madison Aitken, MA,* Thomas D. Steensma, PhD,
†‡
Ray Blanchard, PhD,
§
Doug P. VanderLaan, PhD,*
Hayley Wood, PhD,* Amanda Fuentes, MA,* Cathy Spegg, MBA,
¶
Lori Wasserman, MD,*
Megan Ames, PhD,* C. Lindsay Fitzsimmons, MA,* Jonathan H. Leef, MA,* Victoria Lishak, MA,*
Elyse Reim, MA,* Anna Takagi, MA,* Julia Vinik, PhD,* Julia Wreford, MA,*
Peggy T. Cohen-Kettenis, PhD,
†‡
Annelou L.C. de Vries, MD, PhD,
†,
**
Baudewijntje P.C. Kreukels, PhD,
†‡
and Kenneth J. Zucker, PhD*
*Gender Identity Service, Child, Youth and Family Services, Centre for Addiction and Mental Health, Toronto, Ontario,
Canada;
†
Center of Expertise on Gender Dysphoria, VU University Medical Center, Amsterdam, The Netherlands;
‡
Department of Medical Psychology, VU University Medical Center, Amsterdam, The Netherlands;
§
Department of
Psychiatry, University of Toronto, Toronto, Ontario, Canada;
¶
IM/IT Corporate Applications, Centre for Addiction and
Mental Health, Toronto, Ontario, Canada; **Department of Child and Adolescent Psychiatry, VU University Medical
Center, Amsterdam, The Netherlands
DOI: 10.1111/jsm.12817
ABSTRACT
Introduction. The number of adolescents referred to specialized gender identity clinics for gender dysphoria appears
to be increasing and there also appears to be a corresponding shift in the sex ratio, from one favoring natal males to
one favoring natal females.
Aim. We conducted two quantitative studies to ascertain whether there has been a recent inversion of the sex ratio
of adolescents referred for gender dysphoria.
Methods. The sex ratio of adolescents from two specialized gender identity clinics was examined as a function of two
cohort periods (2006–2013 vs. prior years). Study 1 was conducted on patients from a clinic in Toronto, and Study
2 was conducted on patients from a clinic in Amsterdam.
Results. Across both clinics, the total sample size was 748. In both clinics, there was a significant change in the sex
ratio of referred adolescents between the two cohort periods: between 2006 and 2013, the sex ratio favored natal
females, but in the prior years, the sex ratio favored natal males. In Study 1 from Toronto, there was no corre-
sponding change in the sex ratio of 6,592 adolescents referred for other clinical problems.
Conclusions. Sociological and sociocultural explanations are offered to account for this recent inversion in the sex
ratio of adolescents with gender dysphoria. Aitken M, Steensma TD, Blanchard R, VanderLaan DP, Wood H,
Fuentes A, Spegg C, Wasserman L, Ames M, Fitzsimmons CL, Leef JH, Lishak V, Reim E, Takagi A, Vinik
J, Wreford J, Cohen-Kettenis PT, de Vries ALC, Kreukels BPC, and Zucker KJ. Evidence for an altered sex
ratio in clinic-referred adolescents with gender dysphoria. J Sex Med 2015;12:756–763.
Key Words. Gender Dysphoria; Gender Identity Disorder; Sex Ratio; Adolescents
Introduction
T
he prevalence of gender dysphoria (GD) [1]
is uncertain because of the absence of formal
epidemiological studies. As reviewed by Zucker
and Lawrence [2], prevalence has often been
gauged, at least in adults, by the number of indi-
viduals seeking out hormonal treatment and sex-
reassignment surgery at specialty clinics in
different regions or countries.
Information on the sex ratio of individuals with
GD is one element of these para-epidemiological
studies. In adult samples, in almost all cases, the
number of natal males either exceeds the number
756
J Sex Med 2015;12:756–763 © 2015 International Society for Sexual Medicine
of natal females or the sex ratio is near parity [2,
Table 3] (see also Kreukels et al. [3]).
1
The excep-
tions are studies from Poland and Japan, where the
sex ratio is inverted [4,5]. In clinic-referred child
samples, it has long been noted that the number of
males also exceeds the number of females. Wood
et al. [6], for example, reported a sex ratio of 4.49:1
of boys to girls (N = 577) ages 3–12 years from
their clinic in Toronto, Canada, which was signifi-
cantly higher than the sex ratio of 2.02:1 of boys to
girls (N = 468) in a specialty clinic in Amsterdam,
the Netherlands, but which also favored boys.
Regarding the sex ratio of adolescents referred for
GD, Wood et al. reported a sex ratio of 1.04:1 of
males to females (N = 253) from the Toronto clinic
for the years 1976–2011, which was virtually iden-
tical to the sex ratio of 1.01:1 of males to females
(N = 393) in the Amsterdam clinic (as cited in
Wood et al.).
For many years in the Toronto clinic, the
number of adolescent referrals was quite low.
Between 1976 and 2003, for example, no more
than five adolescents of one biological sex were
assessed in a calendar year and, during this period,
the number of males exceeded the number of
females (Figure 1). Beginning in 2004, however,
the number of adolescent referrals began to rise
quite dramatically [6], which appears to be consis-
tent with the observations of clinicians and
researchers from other gender identity clinics.
Starting in 2006, we noted that the number of
referred female adolescents with GD was now
exceeding the number of referred male adolescents
with GD in the Toronto clinic. Thus, there
appears to be an emerging inversion in the sex
ratio of adolescents with GD which, to our knowl-
edge, has not been documented formally in the
empirical literature.
In Study 1, we analyzed the sex ratio of the
Toronto clinic adolescents and, for comparative
purposes, used an administrative database that
contained information on the sex ratio of adoles-
cent males and females seen clinically for other
psychiatric concerns in our department. The use
of a clinical comparison group allowed us to test
the hypothesis that the temporal shift in the sex
ratio was specific to adolescents with GD but not
clinic-referred adolescents in general. In Study 2,
we analyzed the sex ratio of the Amsterdam clinic
adolescents to test for a temporal shift over the
same time period.
Study 1
Methods
Participants
The probands consisted of 328 adolescents (13–19
years of age) referred to a Gender Identity Service,
housed within the Child, Youth, and Family Ser-
vices (CYFS) at the Centre for Addiction and
Mental Health (CAMH) between 1976 and 2013.
Mean age at the time of assessment was 16.66 years
(standard deviation [SD] = 1.70), and there was no
significant difference in age between the males and
females, t(326) < 1. Depending on the year of
assessment, DSM-III, DSM-III-R, or DSM-IV
criteria were used to diagnose Gender Identity
Disorder (GID) or Gender Identity Disorder Not
Otherwise Specified (GIDNOS) (in DSM-III and
III-R, the diagnostic term was Transsexualism,
not GID, which was first used as the diagnostic
term in the DSM-IV). All probands met criteria
for either GID or GIDNOS. Beginning in 2001,
1
For ease of readability, we truncate hereafter the use of the
terms natal males and natal females to males and females,
respectively.
Figure 1 Number of adolescent pati-
ents assessed by sex and year
Sex Ratio of Adolescents with Gender Dysphoria 757
J Sex Med 2015;12:756–763
we measured the severity of GD in the probands
with the Gender Identity/Gender Dysphoria
Questionnaire for Adolescents and Adults
(GIDYQ-AA) (7). The GIDYQ-AA is a 27-item
questionnaire designed to capture multiple indica-
tors of gender identity and GD, including subjec-
tive, social, somatic, and sociolegal parameters.
Each item was rated on a five-point scale, ranging
from 1 to 5. A lower score indicates more GD.
Based on prior studies, a mean score ≤3.00 indi-
cated “casesness,” with excellent sensitivity and
specificity rates [7,8].
Probands were coded as males or females. The
controls consisted of 6,592 adolescents referred
for other reasons to the CYFS between 1999 and
2013. Controls were referred for many different
reasons, spanning the gamut of psychiatric issues
experienced by youth (e.g., mood and anxiety dis-
orders, disruptive behavior disorders, substance
use disorders, and pervasive developmental disor-
ders). Eleven additional controls were subse-
quently referred to the Gender Identity Service, so
they were not included as clinical controls. The
controls were also coded as males or females.
For the probands, we classified their sexual
orientation as follows: for males, androphilic
vs. nonandrophilic; for females, gynephilic vs.
nongynephilic, as is commonly done for adults
with GD (see Lawrence [9]). This was based either
on clinical chart data or two quantitative measures:
the Erotic Response and Orientation Scale and the
Sexual History Questionnaire [10].
Procedure
The sex of the probands was extracted from an
SPSS file. The sex of the controls was extracted
from an administrative database and converted to
an SPSS file. The database allowed us to eliminate
any duplicate health record numbers and, if such
duplicates were identified, only the first admission
was used. The administrative database of clinical
controls prior to 1999 was no longer accessible.
The study protocol was approved by the CAMH
Research Ethics Board (#004/2014).
Data Analysis
As noted in the Introduction, visual inspection of
the sex ratio for the probands indicated a change
starting in 2006, so, for some of the analyses
reported below, we created two time periods
(1999–2005 and 2006–2013). For both the pro-
bands and the controls, we used a binomial test to
see if there was a significant sex difference in the
proportion of referred males vs. females for each of
the two time periods. We also conducted a logistic
regression that tested for the presence of a
group × time period interaction for the proportion
of referred females.
Results
As noted earlier, there has been a general increase
in the number of referred adolescents (Figure 1).
The correlation between calendar year and the
number of cases assessed in that year was 0.76,
P < 0.001, based on the assumption of a linear rela-
tion between these variables (i.e., the number of
cases increases by roughly the same amount each
year and the graphed data approximate a straight
line). It can, however, be seen in Figure 2 that the
relation between calendar year and the number of
cases assessed was strongly curvilinear. An expo-
nential equation showed that 68% of the variance
in assessments was accounted for by calendar year
(vs. 58% for the linear model).
Table 1 shows the number and percentage of
males vs. females as a function of group × time
Patients
Year
Figure 2 Curvilinear relationship between number of pati-
ents assessed by year (1975–2013)
Table 1 Number and percentage of adolescent referrals
by group and time period
Time period 1999–2005 2006–2013
Group
Gender dysphoria
Males (N/%) 36 (67.9) 73 (36.1)
Females (N/%) 17 (32.1) 129 (63.9)
Sex ratio (M : F) 2.11:1 1:1.76
Clinical controls
Males (N/%) 1,601 (68.9) 2,828 (66.2)
Females (N/%) 721 (31.1) 1,444 (33.8)
Sex ratio (M : F) 2.22:1 1.96:1
758 Aitken et al.
J Sex Med 2015;12:756–763
period. Between 1999 and 2005, a two-tailed bino-
mial test showed that, for the GD group, there was
a greater percentage of males than females
(P = 0.013). In the same time period, for the clini-
cal controls, there was also a greater percentage of
males than females (P < 0.001). Between 2006 and
2013, a binomial test showed that, for the GD
group, there was a greater percentage of females
than males (P < 0.001) but, for the clinical con-
trols, there was a greater percentage of males than
females (P < 0.001). For the time period 1976–
1998, we only had data available on the GD group,
and a binomial test showed that there was a trend
for a greater percentage of males (N = 44) than
females (n = 29) to be referred (P = 0.101).
To examine whether there was evidence for a
group × time period interaction for the proportion
of referred males vs. females, we conducted a logis-
tic regression analysis. The predictor variables
were group (GD vs. controls) × time period
(1999–2005 vs. 2006–2013). We used indicator
coding for these categorical variables. The crite-
rion variable was the sex of the adolescent clients.
Table 2 shows the results of the logistic regres-
sion analysis. The regression equation was built in
two blocks: direct entry of group × time period
(main effects), followed by direct entry of the
interaction term for group × time period. It can
be seen that, in Block 2, there was a significant
group × time period interaction. It can be seen in
Table 1 that the percentage of referred females was
stable for the controls when comparing the two
time periods (1999–2005 vs. 2006–2013). In the
1999–2005 cohort, the percentage of referred GD
females was virtually identical to that of the clinical
control females but, in the 2006–2013 cohort, the
percentage of referred GD females was markedly
higher than the percentage of clinical control
females.
Table 3 shows the number and percentage of
adolescents with GD as a function of sex, sexual
orientation, and time period. We conducted a
logistic regression with sex and sexual orientation
as the predictor variables and time period as the
criterion variable. Table 4 shows that female sex
increased the odds that a proband presented in the
second time period by almost 300% and that a
nonandrophilic sexual orientation (for males) and
a nongynephilic sexual orientation (for females)
increased the odds that a proband presented in
the second time period by over 200%. However,
the sex × sexual orientation interaction was not
significant.
For the 234 probands for whom a GIDYQ-AA
was available, 223 (95.3%) met the criterion for
casesness. To examine whether or not there was a
relationship between severity of GD and year of
assessment, we calculated a Pearson correlation.
For females, the correlation was not significant,
r = 0.026. For males, the correlation was signifi-
cant, r =−0.26, P = 0.011, indicating that more
recently assessed cases had moderately higher GD
severity.
Study 2
Methods
Participants and Procedure
The probands consisted of 420 adolescents (13
years of age and older) referred to the Center of
Table 2 Logistic regression: proportion of adolescent
referred males vs. females by group × time period
Step β SE Wald df Exp(β) P
Block 1
Group 0.98 0.13 58.07 1 2.68 <0.001
Time period 0.16 0.05 8.60 1 1.17 0.003
Block 2
Group × time period 1.19 0.33 12.86 1 3.30 <0.001
Note: Group dummy coded where 0 = clinical controls and 1 = GD probands
and time period 1999–2005 = 0 and 2006–2013 = 1. Sex was dummy coded
as male = 0 and female = 1. Exp(β) is the same as the odds ratio
Table 3 Number and percentage of adolescent referrals
by sex, sexual orientation, and time period
Time period 1976–2005 2006–2013
Group
Males
Androphilic (N/%) 52 (66.7) 32 (43.8)
Nonandrophilic (N/%) 26 (33.3) 41 (56.2)
Females
Gynephilic (N/%) 39 (88.6) 82 (64.0)
Nongynephilic (N/%) 5 (11.4) 46 (36.0)
Note: Sexual orientation is in relation to birth sex. Data on sexual orientation
were not available for 5 probands
Table 4 Logistic regression: number of adolescent
referred males vs. females by sexual orientation
Step β SE Wald df Exp(β) P
Block 1
Sex 1.36 0.26 28.44 1 3.91 <0.001
Sexual orientation 1.11 0.27 16.57 1 3.05 <0.001
Block 2
Sex × sexual orientation 0.53 0.61 0.76 1 1.70 ns
Note: Sex was dummy coded as male = 0 and female = 1. Sexual orientation
was dummy coded as 0 = androphilic or gynephilic and 1 = nonandrophilic or
nongynephilic in relation to birth sex. Exp(β) is the same as the odds ratio
ns = not significant
Sex Ratio of Adolescents with Gender Dysphoria 759
J Sex Med 2015;12:756–763
Expertise on Gender Dysphoria at the VU Uni-
versity Medical Center in Amsterdam, the Neth-
erlands between 1989 and 2013. Mean age at the
time of assessment was 16.14 years (SD = 1.59),
and there was no significant difference in age
between the males and females, t(418) = 1.21. The
sex of the probands was extracted from an SPSS
data file. Extraction of the relevant data was
approved by the Research Ethics Board at the VU
University Medical Center.
Results
Between 1989 and 2005, the number of referred
male adolescents was 109 (58.6%), and the number
of referred female adolescents was 77 (41.4%) (an
M : F sex ratio of 1.41:1), a significant difference
using a binomial test, P = 0.023. Between 2006 and
2013, the number of referred male adolescents was
86 (36.7%), and the number of referred female
adolescents was 148 (63.3%) (an M : F sex ratio of
1:1.72), a significant difference using a binomial
test, P < 0.001. A χ
2
test showed a significant asso-
ciation between the sex distribution of the adoles-
cents and the two time periods, χ
2
(1) = 19.02,
P < 0.001.
The percentage of female adolescents from
Amsterdam in the first time period did not differ
significantly from the percentage of female adoles-
cents from the Toronto clinic, and the percentage
of female adolescents from Amsterdam in the
second time period also did not differ from
the percentage of female adolescents from the
Toronto clinic, both χ
2
(1) < 1.
Discussion
In two independent samples, we found that there
was a significant temporal shift in the sex ratio of
clinic-referred gender-dysphoric youth, from a
ratio favoring males (prior to 2006) to a ratio
favoring females (2006–2013). In Study 1, we
showed that this inversion in the sex ratio was
specific to gender-dysphoric youth and not clinic-
referred adolescents in general. In Study 2, we
found an almost identical shift in the sex ratio of
adolescents assessed at the major gender identity
clinic for adolescents in the Netherlands,
2
thus
matching the findings from Toronto. The sex ratio
favoring females (between 2006 and 2013) is con-
sistent with at least two other recent reports
[11,12]. Becker et al. [11], in Hamburg, Germany,
reported an M : F sex ratio of 1:3.14 (n = 29) for
adolescents with GD assessed between 2006 and
2010 but did not have data for prior years as their
clinic had not yet been established. Spack et al.
(12), in Boston, reported an M : F sex ratio of
1:1.30 (n = 83) for adolescents with GD assessed
between 1998 and 2010 but did not provide data
on any changes in the sex ratio as a function of year
of assessment.
This inversion in the sex ratio of gender-
dysphoric youth is a new development, which
requires an explanation or set of explanations. The
inversion appears to correspond with, albeit inde-
pendently, an increase in the number of clinic-
referred GD youth in general. As noted in Study 1,
we found that there was a very strong curvilinear
correlation between number of cases assessed
annually and year of assessment for adolescents
with GD. This general increase in referrals for GD
is likely due to several factors: the increased
visibility of transgendered people in the media,
which likely contributes to at least a partial
destigmatization of GD; the wide availability of
information on the Internet about transgenderism
or GD, which also likely contributes to destig-
matization; and the increased awareness of the
availability of biomedical treatment for adoles-
cents, including the use of gonadotropin-releasing
hormone agonists to delay or suppress biological
puberty [13,14]. All of these factors have probably
made it easier for youth and their families to seek
out clinical care [15]. It is unclear, however, if these
factors per se would account for the inversion in the
sex ratio, which requires a more nuanced explana-
tion or set of explanations.
In Study 1, we did not find any indication that
there was a significant relationship in females
between severity of GD, as measured by the
GIDYQ-AA, and year of assessment for the time
period 2001–2013 (the period for which we now
had available for analysis this measure). Thus,
there was no evidence in females that the greater
number of referrals in recent years might be
accounted for by an increase in referrals of more
“mild” cases.
3
For males, however, there was a
weak correlation between severity and year of
assessment, but this accounted for only 6.7% of
the variance. Thus, it is unlikely that the recent
2
Prior to 2011, the Centre of Expertise on Gender Dys-
phoria was the sole specialty clinic for children and adoles-
cents in the Netherlands. In 2011, a satellite clinic was
opened in Leiden, but adolescents seen in that clinic were
not part of the Dutch data reported in this study.
3
We would like to thank two of the referees for suggesting
this possibility.
760 Aitken et al.
J Sex Med 2015;12:756–763
inversion in the sex ratio can be accounted for by a
substantive change in severity variation.
One possibility that might explain the inver-
sion of the sex ratio pertains to the well-known
normative sex difference in pubertal onset, in
which females begin puberty, on average, at an
earlier age than males [16]. On the assumption
that our adolescent females with GD began
puberty, on average, at an earlier age than our
adolescent males with GD, perhaps it could be
argued that this results in a relatively greater
salience of the incongruity between their felt
gender identity and their natal sex because this
incongruence began at an earlier age. As a result,
this might explain the greater number of adoles-
cent females presenting with GD than adolescent
males because they experienced a longer period of
distress related to the gender incongruence as a
result of an earlier onset of puberty. If this were
the case, we might have expected that the females
to present at an earlier age than the males.
However, in both studies, the mean age at assess-
ment did not differ significantly between the
females and the males.
A second possibility is related to sexual orienta-
tion. For a long time, it has been argued that sexual
orientation is more variable in biological males
than it is in biological females referred for GD. In
adults with GD, there tends to be a relatively equal
percentage of biological males with an androphilic
vs. a nonandrophilic sexual orientation [17,18].
In contrast, a substantial majority of biological
females have a gynephilic sexual orientation
[17,18]. In recent years, however, more biological
females with a nongynephilic sexual orientation
have been described in the literature (many of
whom identify as gay men after a gender transi-
tion) [19,20]. In the cohort examined in Study 1,
perhaps it could be argued that, in the first time
period, the greater number of biological males
than biological females was an artifact of there
being two prominent subtypes of GD (androphilic
and nonandrophilic) in the former, whereas the
latter were predominantly of only one subtype
(gynephilic), but that this shifted in the second
time period, with a greater number of females with
a nongynephilic sexual orientation. However, the
logistic regression analysis shown in Table 4 did
not provide evidence for a sex × sexual orientation
interaction. It only showed that a nonandrophilic
or nongynephilic sexual orientation increased the
odds that a proband presented in the second time
period, but sexual orientation did not interact with
probands’ biological sex.
Might sociological or sociocultural factors
account for the recent inversion in the sex ratio? It
is well-known that individuals with GD who are
sexually attracted to members of their birth sex
have an early-onset (i.e., in childhood) history of
marked cross-gender (gender-variant) behavior, a
developmental parameter that is similar to that of
some gay men and lesbians [21], who also have a
childhood history of cross-gender behavior. Pro-
spective studies of GD in children suggest that the
degree of cross-gender behavior is predictive of
GD persistence into adolescence and adulthood,
with many of the desisters differentiating a same-
sex sexual orientation [22–24]. Nonetheless, there
is a good deal of overlap in the degree of child-
hood cross-gender behavior between individuals
with an early-onset of GD and some gay men and
lesbians. For example, Lee [25] noted that the
developmental histories of “butch lesbians” and
female-to-male transsexuals showed many simi-
larities, and it was difficult to predict, on an indi-
vidual basis, which “group” these females would
wind up in.
Given that there is at least some overlap in the
gender-variant developmental histories of early-
onset individuals with GD and some gay men and
lesbians, it might, therefore, be asked whether or
not degree of stigmatization for gender-variant
behavior might account for the recent inversion in
the sex ratio of GD adolescents. It is well-known
that cross-gender behavior in children is subject to
more social stigma (e.g., peer rejection and peer
teasing) in males than in females, in both clinic-
referred adolescents with GD and in the general
population [26–30]. Thus, it could be argued that
it is easier for adolescent females to “come out” as
transgendered than it is for adolescent males to
come out as transgendered because masculine
behavior is subject to less social sanction than
feminine behavior. Some support for this was
found in Shiffman’s [31] study of peer relations in
adolescents with GD, in which adolescent males
with GD reported more “social bullying” than
adolescent females with GD. Given that a
transgendered identity as an “identity option” has
become much more visible over the past decade, it
is conceivable, therefore, that such an identity
option is easier for females to declare than it is for
males because it does not elicit as much of a nega-
tive response. Thus, it could be argued that it is
this sex difference in degree of stigmatization that
accounts for the inversion in the sex ratio that we
have identified in the two studies reported here. In
other words, there are greater costs for a male to
Sex Ratio of Adolescents with Gender Dysphoria 761
J Sex Med 2015;12:756–763
adopt a female gender identity in adolescence than
it is for a female to adopt a male gender identity.
Corresponding Author: Kenneth J. Zucker, PhD,
Gender Identity Service, Child, Youth and Family Ser-
vices, Centre for Addiction and Mental Health, 80
Workman Way, 5th Floor, Toronto, Ontario M6J 1H4,
Canada. Tel: 4165358501; Fax: 4169794996; E-mail:
Ken.Zucker@camh.ca
Conflict of Interest: The author(s) report no conflicts of
interest.
Statement of Authorship
Category 1
(a)
Conception and Design
Kenneth J. Zucker; Madison Aitken; Thomas D.
Steensma
(b)
Acquisition of Data
Kenneth J. Zucker; Cathy Spegg; Thomas D.
Steensma
(c)
Analysis and Interpretation of Data
Kenneth J. Zucker; Ray Blanchard; Doug P.
VanderLaan; Thomas D. Steensma
Category 2
(a)
Drafting the Article
Kenneth J. Zucker
(b)
Revising It for Intellectual Content
Madison Aitken; Doug P. VanderLaan; Hayley
Wood; Amanda Fuentes; Lori Wasserman; Megan
Ames; C. Lindsay Fitzsimmons; Jonathan H. Leef;
Victoria Lishak; Elyse Reim; Anna Tagaki; Julia
Vinik; Julia Wreford; Peggy T. Cohen-Kettenis;
Annelou L. C. de Vries; Baudewijntje P. C. Kreukels
Category 3
(a)
Final Approval of the Completed Article
Kenneth J. Zucker; Thomas D. Steensma
References
1 American Psychiatric Association. Diagnostic and statistical
manual of mental disorders. 5th edition. Arlington, VA: Ameri-
can Psychiatric Press; 2013.
2 Zucker KJ, Lawrence AA. Epidemiology of gender identity
disorder: Recommendations for the standards of care of the
World Professional Association for Transgender Health. Int J
Transgenderism 2009;11:8–18.
3 Kreukels BPC, Harldsen IR, De Cuypere G, Richter-Appelt
H, Gijs L, Cohen-Kettenis PT. A European network for the
investigation of gender incongruence: The ENIGI initiative.
Eur Psychiatry 2012;27:445–50.
4 Baba T, Endo T, Ikeda K, Shimizu A, Honnma H, Ikdeda H,
Masumori N, Ohmura T, Kiya T, Fujimoto T, Koizumi M,
Saito T. Distinctive features of female-to-male transsexualism
and prevalence of gender identity disorder in Japan. J Sex Med
2011;8:1686–93.
5 Godlewski J. Transsexualism and anatomic sex ratio reversal in
Poland. Arch Sex Behav 1988;17:547–8.
6 Wood H, Sasaki S, Bradley SJ, Singh D, Fantus S,
Owen-Anderson A, Di Giacomo A, Bain J, Zucker KJ.
Patterns of referral to a Gender Identity Service for Children
and Adolescents (1976–2011): Age, sex ratio, and sexual
orientation [Letter to the Editor]. J Sex Marital Ther
2013;39:1–6.
7 Singh D, Deogracias JJ, Johnson LJ, Bradley SJ, Kibblewhite
SJ, Owen-Anderson A, Peterson-Badali M, Meyer-Bahlburg
HFL, Zucker KJ. The gender identity/gender dysphoria ques-
tionnaire for adolescents and adults: Further validity evidence.
J Sex Res 2010;47:49–58.
8 Deogracias JJ, Johnson LL, Meyer-Bahlburg HFL, Kessler SJ,
Schober JM, Zucker KJ. The gender identity/gender dyspho-
ria questionnaire for adolescents and adults. J Sex Res
2007;44:370–9.
9 Lawrence AA. Sexual orientation versus age of onset as bases
for typologies (subtypes) for gender identity disorder in ado-
lescents and adults. Arch Sex Behav 2014;39:514–45.
10 Zucker KJ, Bradley SJ, Owen-Anderson A, Kibblewhite SJ,
Wood H, Singh D, Choi K. Demographics, behavior prob-
lems, and psychosexual characteristics of adolescents with
gender identity disorder or transvestic fetishism. J Sex Marital
Ther 2012;38:151–89.
11 Becker I, Gjergji-Lama V, Romer G, Möller B. Merkmale
von Kindern und Jugendlichen mit Geschlechtsdysphoria in
der Hamburger Spezialsprechstunde. Prax Kinderpsychol
Kinderpsychiat 2014;63:486–509.
12 Spack NP, Edwards-Leeper M, Feldman HA, Leibowitz S,
Mandel F, Diamond DA, Vance SR. Children and adolescents
with gender identity disorder referred to a pediatric medical
center. Pediatrics 2012;129:418–25.
13 Cohen-Kettenis PT, Steensma TD, de Vries ALC.
Treatment of adolescents with gender dysphoria in the
Netherlands. Child Adolesc Psychiatr Clin N Am 2011;20:
689–700.
14 Zucker KJ, Bradley SJ, Owen-Anderson A, Singh D,
Blanchard R, Bain J. Puberty-blocking hormonal therapy
for adolescents with gender identity disorder: A descriptive
clinical study. J Gay Lesbian Ment Health 2011;15:58–
82.
15 Hsieh S, Leininger J. Resource list: Clinical care programs for
gender-nonconforming children and adolescents. Pediatr Ann
2014;43:238–44.
16 Sizonenko PC. Normal sexual maturation. Pediatrician
1987;14:191–201.
17 Blanchard R, Clemmensen L, Steiner BW. Heterosexual and
homosexual gender dysphoria. Arch Sex Behav 1985;16:139–
52.
18 Nieder TO, Herff M, Cerwenka S, Preuss WF,
Cohen-Kettenis PT, De Cuypere G, Haraldsen IRH,
Richter-Appelt H. Age of onset and sexual orientation in trans-
sexual males and females. J Sex Med 2011;8:783–91.
19 Bockting W, Benner A, Coleman E. Gay and bisexual identity
development among female-to-male transsexuals in North
America: Emergence of a transgender sexuality. Arch Sex
Behav 2009;38:688–701.
20 Meier SC, Pardo ST, Labuski C, Babcock J. Measures of
clinical health among female-to-male transgender persons as a
function of sexual orientation. Arch Sex Behav 2013;42:463–
74.
21 Bailey JM, Zucker KJ. Childhood sex-typed behavior and
sexual orientation: A conceptual analysis and quantitative
review. Dev Psychol 1995;31:43–55.
22 Singh D. A follow-up study of boys with gender identity
disorder. Unpublished doctoral dissertation, University of
Toronto, Toronto, Ontario, 2012.
762 Aitken et al.
J Sex Med 2015;12:756–763
23 Steensma TD, McGuire JK, Kreukels BPC, Beekman AJ,
Cohen-Kettenis PT. Factors associated with desistence and
persistence of childhood gender dysphoria: A quantitative
follow-up study. J Am Acad Child Adolesc Psychiatry
2013;52:582–90.
24 Wallien MSC, Cohen-Kettenis PT. Psychosexual outcome of
gender dysphoric children. J Am Acad Child Adolesc Psychia-
try 2008;47:1413–23.
25 Lee T. Trans(re)lations: Lesbian and female to male transsexual
accounts of identity. Women’s Stud Int Forum 2001;24:347–57.
26 Cohen-Kettenis PT, Owen A, Kaijser VG, Bradley SJ, Zucker
KJ. Demographic characteristics, social competence, and
behavior problems in children with gender identity disorder: A
cross-national, cross-clinic comparative analysis. J Abnorm
Child Psychol 2003;31:41–53.
27 Fagot BI. Consequences of moderate cross-gender behavior in
preschool children. Child Dev 1977;48:902–7.
28 Green R, Williams K, Harper J. Cross-sex identity: Peer
group integration and the double standard of childhood
sex-typing. In: Samson J, ed. Childhood and sexuality.
Montreal: Editions Etudes Vivantes; 1980:542–8.
29 Wallien MSC, Veenstra R, Kreukels BPC, Cohen-Kettenis
PT. Peer group status of gender dysphoric children: A socio-
metric study. Arch Sex Behav 2010;39:553–60.
30 Zucker KJ, Wilson-Smith DN, Kurita JA, Stern A. Children’s
appraisals of sex-typed behavior in their peers. Sex Roles
1995;33:703–25.
31 Shiffman M. Peer relations in adolescents with gender identity
disorder. Unpublished doctoral dissertation, University of
Guelph, Guelph, Ontario, 2013.
Sex Ratio of Adolescents with Gender Dysphoria 763
J Sex Med 2015;12:756–763
