According to the 2015 U.S. Transgender Survey (USTS), which is "the largest survey of transgender people in the U.S. to date":
According to a 2019 report from the Williams Institute at the UCLA School of Law, "[T]ransgender adults have a prevalence of past-year suicide ideation that is nearly twelve times higher, and a prevalence of past-year suicide attempts that is about eighteen times higher, than the U.S. general population."
A study of over 130,000 students, published in Frontiers in Psychology in 2021, compared "involvement in bullying between transgender and mainstream youth and among middle and late adolescents in a general population sample" and found:
A 2011 study in PLOS One found, “Persons with transsexualism, after sex reassignment, have considerably higher risks for mortality, suicidal behaviour, and psychiatric morbidity than the general population. Our findings suggest that sex reassignment, although alleviating gender dysphoria, may not suffice as treatment for transsexualism, and should inspire improved psychiatric and somatic care after sex reassignment for this patient group.”
An article published in the Journal of Medical Ethics in 2019 assessed the fairness of International Olympic Committee guidelines, which "allow transwomen to compete in the women’s division if (amongst other things) their testosterone is held below 10 nmol/L."
The article found:
Research published in the British Journal of Sports Medicine in 2021 "reviewed fitness test results and medical records of 29 transmen and 46 transwomen who started gender affirming hormones while in the United States Air Force."
Before gender-affirming hormones, “[T]ranswomen performed 31% more push-ups and 15% more sit-ups in 1 min and ran 1.5 miles 21% faster than their female counterparts," per the authors of the study.
Following two years of feminizing hormones, “the push-up and sit-up differences disappeared but transwomen were still 12% faster," the study revealed.
A study published in the Journal of Clinical Endocrinology & Metabolism in 2019 "explored the effects of gender-affirming treatment on muscle function, size, and composition during 12 months of therapy" in 11 transwomen and 12 transmen.
The study found that the transgender women “generally maintained their strength levels” after a year of treatment.
An article published in Sports Medicine in 2021 explored performance disparities between males and females and assessed the advantages enjoyed by transgender women in sports.
The article found:
A study published in PLOS One in 2018 surveyed the parents of adolescent and young adult (AYA) children who showed signs "of an apparent sudden or rapid onset of gender dysphoria that began during or after puberty.”
The study, authored by Lisa Littman of Brown University, found:
A 2021 systematic review of studies examining the effects of hormone transition, published in the British Journal of Sports Medicine, found: