The practice of medically transitioning minors, currently referred to as "gender-affirmative care," began to gain momentum following a single-site study in the Netherlands. Previously, gender transition was available only to mature adults, with the average age of transition frequently in the 30's. However, it was noted that the results of adult transitions were frequently disappointing, which was believed to be explained by unsatisfactory cosmetic outcomes, particularly for males, who had a "never disappearing masculine appearance." in the 1990's, the Dutch clinicians began to experiment with transitioning minors using endocrine interventions with the hope that a better cosmetic outcome would also lead to better mental health ones. The results of the innovative Dutch experiment, which has become known as "the Dutch Protocol," were documented in two publications: the 2011 study, which reported on cases who underwent puberty blockade, and the 2014 study, which reported on a subset of the cases who completed surgeries, including the removal of ovaries and testes upon reaching the age of 18.
The youth in the Dutch study reported high levels psychological functioning at 1.5 years after surgery, the study end point. However, both of the studies suffer from a high risk of bias due to their study design and suffer from limited applicability to the populations of adolescents presenting today According to a recently-published overview of the Dutch protocol, the interventions described in the study are currently being applied in the way there were not intended. Specifically, adolescents who were not cross-gender identified prior to puberty, who have significant mental health problems, as well as those who have non-binary identities are now commonly treated using endocrine and surgical interventions described by the Dutch—yet all of these presentations were explicitly disqualified from the Dutch protocol.
The study itself suffers from significant limitations, ranging from a weak study design, only marginal improvements in psychological function, and number of under-reported adverse health events that occurred over the course of they study (including 1 case of death and 3 cases of severe morbidity). Researchers have also questions the validity of the gender dysphoria resolution reported by the Dutch, in light of their unusual handling of the gender dysphoria scale. Despite these limitations, the Dutch clinical experiment has become the basis for the practice of medical transition of minors worldwide and serves as the basis for the recommendations outlined in the 2017 Endocrine Society guidelines and has given rise to the so-called "gender affirmative" model of care for youth, which requires access to puberty blockers, hormones, and potentially surgery.