Puberty

Puberty is the process of physical maturation, during which there is an acceleration in growth in stature, secondary sexual characteristics appear and develop, and the ability to reproduce is achieved.

For transgender (trans) youth, the onset of puberty may mark the beginning of permanent and visible changes that may result in, or worsen, gender dysphoria. In this context, it is important to understand the concept of puberty, its timing, and its stages in order to tailor clinical interventions for youth who require them.

Puberty onset varies between sexes, appearing on average earlier in youth assigned female at birth (AFAB) around 10 to 11 years of age, compared with those assigned male at birth (AMAB) around 11 to 12 years of age. Aside from biological sex, timing of puberty varies across races, with an earlier onset in Black AFAB youth. It has also been noted that puberty is starting at increasingly younger ages on average, presumably as a result of positive factors such as improved nutrition, as well as a result of obesity (specifically in AFAB youth) and various potentially noxious environmental exposures (e.g., certain pesticides). Although the factors that determine the onset of puberty are not fully understood, it has been determined that puberty starts when the hypothalamus begins releasing gonadotropin-releasing hormone (GnRH). This production of GnRH begins to occur in pulses, and it is this pulsatile release that stimulates secretion of the gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), from the anterior pituitary. Growth of ovaries or testes occurs as a result of the rising levels of LH and FSH, and these organs begin to produce estradiol (estrogen) and testosterone, respectively.

Pubertal development can be assessed by quantifying changes in breast development and pubic hair appearance and pattern for youth AFAB and genital changes (testicular and penile) and pubic hair for youth AMAB. The sexual maturity rating (SMR), also known as Tanner staging, is used to assess the progress through puberty and graded as 1, for prepubertal characteristics, through 5, for fully developed secondary sexual characteristics, with progressive and defined stages in between.