Puberty can be especially upsetting for many transgender children. Starting at the first signs of the changes — around 10 years old for girls, and 11 for boys — doctors can prescribe hormone blockers, which are injections or implants that keep the body from releasing estrogen or testosterone. That means the body won’t go through the permanent changes that normally happen during puberty, such as growing facial hair, getting an Adam’s apple, voice changes, breast growth, and the start of menstrual periods. But the effects of the medication are reversible. Your child could decide later to stop taking them and go through the physical changes of their biological sex.