Archives of Sexual Behavior
Sex Ratio inChildren andAdolescents Referred totheGender Identity
Development Service intheUK (2009–2016)
NastasjaM.deGraaf1,2· GuidoGiovanardi1,3· ClaudiaZitz1· PollyCarmichael1
Received: 12 February 2018 / Accepted: 21 March 2018
© Springer Science+Business Media, LLC, part of Springer Nature 2018
Over the last decade, several child and adolescent gender iden-
tity services have reported an increase in young people who
seek help with incongruence between the experienced gender
identity and the gender to which they were assigned at birth
(Aitken etal., 2015; Wood etal., 2013). Many of those, but not
all, would meet the diagnostic criteria for gender dysphoria
(GD) (APA, 2013). It has been suggested that this increase
is mostly due to an inﬂux of birth-assigned females coming
forward. Aitken etal. (2015) reported a signiﬁcant temporal
shift in the sex ratio of clinic-referred gender-diverse youth to
Toronto and Amsterdam, from a ratio favoring males prior to
2006, to a ratio favoring assigned females from 2006 to 2013.
The national Gender Identity Development Service (GIDS)
in the UK is the largest child and adolescent specialist gen-
der service in the world, seeing young people up to the age of
18. Historically, more birth-assigned males were presenting
to GIDS in childhood and adolescence (Di Ceglie, Freedman,
McPherson, & Richardson, 2002). However, in a more recent
study, adolescent referrals to GIDS favored birth-assigned
females (de Graaf etal., 2017; Holt, Skagerberg, & Dunsford,
Gender-diverse young people often present with psycho-
logical diﬃculties. Compared to children, a greater percent-
age of gender-diverse adolescents have psychological diﬃcul-
ties in the clinical range (Steensma etal., 2014). The level of
psychological well-being for birth-assigned males and females
referred in childhood are often comparable (Steensma etal.,
2014). In adolescents, however, gender diﬀerences in psycho-
logical functioning are noted more frequently. The literature
suggests that birth-assigned males tend to show more internaliz-
ing diﬃculties in the clinical range than birth-assigned females
(de Vries, Steensma, Cohen-Kettenis, VanderLaan, & Zucker,
2016). However, more recently, increased psychopathology
was also reported for gender-diverse birth-assigned females
(de Graaf etal., 2017; Kaltiala-Heino, Sumia, Työläjärvi, &
The current study aimed to examine the sex ratio in the num-
ber of children and adolescents referred to GIDS over the past
7years and to investigate whether any gender diﬀerences can be
found in terms of psychological functioning and age at referral.
For this retrospective review of GIDS referrals, exemption
for ethics was conﬁrmed by external and local ethics commit-
tees aﬃliated with the Tavistock and Portman NHS Research
and Development Department. Between January 1, 2009,
and December 31, 2016, a total of 4506 young people, aged
between 1 and 18years, were referred to GIDS. Age at refer-
ral and birth-assigned gender were collected at time of refer-
ral. The sex ratio for children and adolescents was tested for
signiﬁcance using the binomial test. Age at referral was ana-
lyzed per year using independent t tests. The Child Behavior
Checklist (CBCL), which was completed by the parent during
the assessment phase, was used to measure internalizing and
externalizing clinical range scores (T scores > 63) (Achenbach
& Edelbrock, 1983). The CBCL data were analyzed by birth-
assigned gender in children and adolescents using a chi-square
test with a two-tailed p value. CBCL data were available for
39% of all child cases. In the adolescent sample, 60% had a
completed CBCL. One explanation for the high number of
missing CBCL data could have to do with service users not
* Nastasja M. de Graaf
1 Gender Identity Development Service, Tavistock
andPortman NHS Foundation Trust, 120 Belsize Lane,
2 Department ofMedical Psychology, Center ofExpertise
onGender Dysphoria, VU University Medical Center,
3 Department ofDynamic andClinic Psychology, Faculty
ofMedicine andPsychology, Sapienza University ofRome,
Archives of Sexual Behavior
always returning questionnaires when receiving these after their
ﬁrst appointment. The higher percentage of missing data in the
child group could relate to the fact that a greater proportion of
younger children may not be seen as frequently as adolescents,
and possibly dropout during the assessment phase.
Characteristics of GIDS referrals, of which the vast majority
(84%) were adolescents, are shown in Table1. A signiﬁcant
diﬀerence by the binomial test, p < .001, showed that the sex
ratio in children favored birth-assigned males (M/F, 1.31:1),
whereas in adolescents referrals favored birth-assigned females
(M/F, 1:2.12), binomial test, p < .001. Interestingly, in both
children and adolescents, the average increase rate of referrals
was higher for birth-assigned females, as displayed in Fig.1.
For age at referral in children, birth-assigned males were,
on average, referred at a younger age, t(717) = 4.05, p < .001,
whereas in adolescents birth-assigned females were younger,
t(3785) = − 2.91, p < .005. No significant differences were
found over time, which indicates that the age at referral for
birth-assigned males and birth-assigned females in children and
adolescents has remained stable over the last 7years.
With regard to psychological functioning, a signifi-
cantly greater percentage of adolescents had Internalizing
problems in the clinical range compared to children, χ2(1,
N = 1696) = 12.02, p < .001. For this comparison, however,
there is a sex diﬀerence: the diﬀerence between children and
adolescents is signiﬁcant only for birth-assigned females, χ2(1,
N = 1127) = 11.17, p < .001, and not for birth-assigned males,
χ2(1, N = 569) = .37, p = .54. On the other hand, Externalizing
problems were signiﬁcantly more prevalent in children than
in adolescents, χ2(1, N = 1696) = 39.92, p < .001. For adoles-
cents, a greater percentage of birth-assigned females showed
Internalizing problems in the clinical range compared to birth-
assigned males, χ2(1, N = 1468) = 16.47, p < .001, whereas a
signiﬁcantly greater percentage of birth-assigned males scored
in the Externalizing clinical range compared to birth-assigned
females, χ2(1, N = 1468) = 4.36, p < .05. For children, no sig-
niﬁcant gender diﬀerences were found on both Internalizing,
χ2(1, N = 228) = .01, p = .91, and Externalizing scales, χ2(1,
N = 228) = .00, p = 1.0.
The UK has witnessed an unprecedented increase in referrals
of gender-diverse young people seeking professional help. Both
in children and adolescents the rise in referrals was steeper for
birth-assigned females compared to birth-assigned males. This
has resulted in an inversion in sex ratio in adolescent referrals
and an evening out of birth-assigned male and female refer-
rals in childhood. While the overall number of birth-assigned
female referrals has increased, the age at which referrals were
made did not change over time.
Table 1 Characteristics of
GIDS referrals and CBCL
CBCL Child Behavior Checklist
Children (< 12years) Adolescents (12–18years)
(N = 719) (N = 3787)
Assigned males Assigned females Assigned males Assigned females
Total N408 311 1210 2577
Sex ratio 56.7% 43.3% 32.0% 68.0%
Increase in referrals year on year
2009N10 2 24 15
2010% (N) 90% (19) 250% (7) 83% (44) 220% (48)
2011% (N) 53% (29) 71% (12) 0% (41) 63% (78)
2012% (N) 3% (30) 42% (17) 88% (77) 81% (141)
2013% (N) 3% (31) 29% (22) 56% (120) 57% (221)
2014% (N) 77% (55) 64% (36) 54% (185) 42% (314)
2015% (N) 87% (103) 114% (77) 58% (293) 102% (689)
2016% (N) 27% (131) 79% (138) 45% (426) 55% (1071)
Average % increase 48.6% 92.7% 54.9% 88.6%
Mean age at referral (M, SD) 8.27 (2.27) 8.97 (2.34) 15.59 (1.40) 15.45 (1.32)
CBCL clinical range (N) 119 109 450 1018
Internalizing problems % (N) 52.1% (62) 50.5% (55) 55.8% (251) 67.0% (682)
Externalizing problems % (N) 35.3% (42) 34.9% (38) 20.2% (91) 15.6% (159)
Archives of Sexual Behavior
Compared to international data reported by other gender
identity clinics, the sex ratio of the child referrals in the UK was
more in line with the child sex ratio reported by the Amster-
dam clinic (1.25:1, N = 860) than with the Toronto clinic, which
reported a larger proportion of birth-assigned males referred
in childhood (4.33:1, N = 624) (Steensma, Cohen-Kettenis, &
Zucker, 2018). While across all three clinics birth-assigned boys
were signiﬁcantly younger than the referred girls in childhood,
the mean age of the children referred in Toronto was signiﬁ-
cantly younger at referral compared to Amsterdam and the UK.
As suggested by de Vries etal. (2016), these outcomes could
reﬂect that there are cultural diﬀerences between North America
and Europe, speciﬁcally with regard to tolerance or acceptance
of gender-diverse behavior, particularly in birth-assigned boys.
For adolescents, our ﬁndings reﬂect the general trend of an
inversion in sex ratios reported both in Amsterdam and Toronto
(in Amsterdam: 1:1.72, N = 234; in Toronto: 1:1.76, N = 202;
Aitken etal., 2015), in the U.S. (1:1.4, N = 180; Reisner etal.,
2015), and more pronounced in Germany (1:2.9, N = 39;
Becker, Ravens-Sieberer, Ottová-Jordan, & Schulte-Markwort,
2017) and Finland (1:6.8, N = 49; Kaltiala-Heino etal., 2015).
There are various explanations put forward in the literature
contemplating the increase in birth-assigned females. Some
have suggested that diﬀerences in normative sex development,
in which birth-assigned females experience pubertal changes at
an earlier age than birth-assigned males, might have an impact
on the greater number of adolescent birth-assigned females
coming forward (Aitken etal., 2015). However, as the increase
in birth-assigned female referrals was found across the age
range, arguments around timing of puberty cannot fully explain
the rising number of birth-assigned females. Several clinical
observations suggest that pre-pubertal young people, speciﬁ-
cally girls, may experience adversity toward puberty (Harris,
2004; Lesko, 2012; Pinto, 2007). Therefore, rather than the
experience of puberty, could we argue that birth-assigned
females in childhood are increasingly more worried about the
thought of puberty?
Other arguments regarding the influx in birth-assigned
females suggest that, given the increased awareness and vis-
ibility of declaring trans identities, “coming out” in this context
may be easier for birth-assigned females than it is for birth-
assigned males (Aitken etal., 2015). This argument can be
supported by the claim that gender-variant behavior in birth-
assigned males may be more exposing and can lead to social
stigma (Shiﬀman etal., 2016).
Additionally, the digitalization of the ways in which young
people and society communicate should not be underestimated.
Social media is increasingly used as a platform to seek peer
group belonging and support, especially by adolescent girls
(Barker, 2009). In the current context, with increasingly more
birth-assigned females referred to gender services present-
ing with psychopathology, could we argue that inﬂuences of
socially constructed views of “femininity” and “masculinity”
and the way these are being displayed on social media may have
an impact on the increase of birth-assigned female referrals,
especially for those who do not feel they ﬁt this stereotype?
AFAB = assigned fema le at birth; AMAB = assigned male at birth
*Indicates p< .05 which shows a significant increase of referrals compared to the previous year
2009 2010 2011 2012 2013 2014 2015 2016
Adolescents F15 48 78 141 221 314 689 1071
Adolescents M24 44 41 77 120 185 293 426
Children F2712 17 22 36 77 138
Children M10 19 29 30 31 55 103 131
Fig. 1 Number of GIDS referrals per year for child (< 12 years) and
adolescent (12–18 years) birth-assigned females and birth-assigned
males. AFAB assigned female at birth, AMAB assigned male at birth.
*Indicates p < .05 which shows a signiﬁcant increase in referrals com-
pared to the previous year
Archives of Sexual Behavior
Psychopathology in adolescent birth-assigned females is a
topical issue which is currently reported by various interna-
tional gender identity clinics (de Graaf etal., 2017; Kaltiala-
Heino etal., 2015). Not only adolescent girls, also a greater
percentage of referred birth-assigned males presented with
externalizing problems in the clinical range in adolescence,
which could reﬂect the current changing climate. Whereas
adolescents tend to report more behavioral and emotional
problems than children, in our sample, a greater percentage
of children had externalizing problems in the clinical range
compared to the adolescents. When comparing these ﬁndings
to previously published outcomes from the Toronto clinic and
the Amsterdam clinic (Steensma etal., 2014), a greater percent-
age of children in the UK had internalizing and externalizing
problems in the clinical range. The increase in psychopathology
mirrors a general trend of young people in the UK, especially
in adolescent girls (Lessof etal., 2016). A new phenomenon,
however, is the increase in referred birth-assigned females in
late childhood, which is also reported by other gender iden-
tity clinics (Steensma etal., 2018). With the inﬂux of birth-
assigned females starting in childhood, we might expect to see
an increase in behavioral problems in children, especially those
The steep increase in birth-assigned females seeking help
from gender services across the age range highlights an emerg-
ing phenomenon. It is important to follow birth-assigned
females’ trajectories, to better understand the changing clinical
presentations in gender-diverse children and adolescents and to
monitor the inﬂuence of social and cultural factors that impact
on their psychological well-being.
Compliance with Ethical Standards
Conflict of interest The authors declare there is no conﬂict of interest.
There was no sponsor involved in this Letter. The authors disclose that
there are no prior publications or submissions with any overlapping in-
formation of this kind.
Achenbach, T. M., & Edelbrock, C. S. (1983). Manual for the child
behavior checklist and revised child behavior proﬁle. Burlington:
Department of Psychiatry, University of Vermont.
Aitken, M., Steensma, T. D., Blanchard, R., VanderLaan, D. P., Wood,
H., Fuentes, A., … Zucker, K. J. (2015). Evidence for an altered
sex ratio in clinic-referred adolescents with gender dysphoria.
Journal of Sexual Medicine, 12, 756–763.
American Psychiatric Association. (2013). Diagnostic and statistical
manual of mental disorders (5th ed.). Arlington, VA: American
Barker, V. (2009). Older adolescents’ motivations for social network
site use: The inﬂuence of gender, group identity, and collective
self-esteem. Cyberpsychology and Behavior, 12, 209–213.
Becker, I., Ravens-Sieberer, U., Ottová-Jordan, V., & Schulte-Mark-
wort, M. (2017). Prevalence of adolescent gender experiences
and gender expression in Germany. Journal of Adolescent Health,
61, 83–90. https ://doi.org/10.1016/j.jadoh ealth .2017.02.001.
de Graaf, N. M., Cohen-Kettenis, P. T., Carmichael, P., de Vries, A. L.
C., Dhondt, K., Laridaen, J., … Steensma, T. D. (2017). Psycholog-
ical functioning in adolescents referred to specialist gender identity
clinics across Europe: A clinical comparison study between four
clinics. European Child and Adolescent Psychiatry. https ://doi.
de Vries, A. L., Steensma, T. D., Cohen-Kettenis, P. T., VanderLaan, D.
P., & Zucker, K. J. (2016). Poor peer relations predict parent-and
self-reported behavioral and emotional problems of adolescents
with gender dysphoria: A cross-national, cross-clinic comparative
analysis. European Child and Adolescent Psychiatry, 25, 579–588.
Di Ceglie, D., Freedman, D., McPherson, S., & Richardson, P. (2002).
Children and adolescents referred to a specialist Gender Identity
Development Service: Clinical features and demographic charac-
teristics. International Journal of Transgenderism, 6(1). Retrieved
August 3, 2013, from http://www.sympo sion.com/ijt/ijtvo 06no0
Harris, A. (2004). Future girl: Young women in the twenty-ﬁrst century.
New York: Routledge.
Holt, V., Skagerberg, E., & Dunsford, M. (2016). Young people with
features of gender dysphoria: Demographics and associated dif-
ﬁculties. Clinical Child Psychology and Psychiatry, 21, 108–118.
Kaltiala-Heino, R., Sumia, M., Työläjärvi, M., & Lindberg, N. (2015).
Two years of gender identity service for minors: Overrepresenta-
tion of natal girls with severe problems in adolescent development.
Child and Adolescent Psychiatry and Mental Health, 9(1), 9. https
Lesko, N. (2012). Act your age! A cultural construction of adolescence.
New York: Routledge.
Lessof, C., Ross, A., Brind, R., Bell, E., & Newton, S. (2016). Longi-
tudinal study of young people in England: Cohort 2: Health and
wellbeing at Wave 2. London: Department for Education.
Pinto, K. (2007). Growing up young: The relationship between child-
hood stress and coping with early puberty. Journal of Early Adoles-
cence, 27, 509–544. https ://doi.org/10.1177/02724 31607 30293 6.
Reisner, S. L., Vetters, R., Leclerc, M., Zaslow, S., Wolfrum, S., Shumer,
D., etal. (2015). Mental health of transgender youth in care at an
adolescent urban community health center: A matched retrospec-
tive cohort study. Journal of Adolescent Health, 56, 274–279. https
://doi.org/10.1016/j.jadoh ealth .2014.10.264.
Shiﬀman, M., VanderLaan, D. P., Wood, H., Hughes, S. K., Owen-
Anderson, A., Lumley, M. M., … Zucker, K. J. (2016). Behavio-
ral and emotional problems as a function of peer relationships in
adolescents with gender dysphoria: A comparison with clinical
and nonclinical controls. Psychology of Sexual Orientation and
Gender Diversity, 3, 27–36.
Steensma, T. D., Cohen-Kettenis, P. T., & Zucker, K. J. (2018). Evidence
for a change in the sex ratio of children referred for gender dys-
phoria: Data from the Center of Expertise on Gender Dysphoria in
Amsterdam (1988–2016) [Letter to the Editor]. Journal of Sex and
Marital Therapy. https ://doi.org/10.1080/00926 23X.2018.14375
Steensma, T. D., Zucker, K. J., Kreukels, B. P., VanderLaan, D. P.,
Wood, H., Fuentes, A., etal. (2014). Behavioral and emotional
problems on the Teacher’s Report Form: A cross-national, cross-
clinic comparative analysis of gender dysphoric children and ado-
lescents. Journal of Abnormal Child Psychology, 42, 635–647.
Wood, H., Sasaki, S., Bradley, S. J., Singh, D., Fantus, S., Owen-Ander-
son, A., … Zucker, K. J. (2013). Patterns of referral to a Gender
Identity Service for Children and Adolescents (1976–2011): Age,
sex ratio, and sexual orientation [Letter to the Editor]. Journal of
Sex and Marital Therapy, 39, 1–6. https ://doi.org/10.1080/00926