From this perspective, sexual experiences such as coitus are seen as fundamentally transformative, marking an irreversible status boundary between adolescence and adulthood. We're not just going to give you the facts on sexual development — we're also going to tell you the messages that we think children should be receiving as they go through the different stages of sexual development. These findings could be used to indicate which kids may be at greater risk for teen pregnancy and sexually transmitted diseases because they began sex early, said Dr. Cora Breuner, a pediatrician at Seattle Children's Hospital and a member of the American Academy of Pediatrics' committee on adolescence. This is because hormone levels vary during the menstrual cycle. Teens need to recognize that sexual wishes or fantasies are normal, and that we do not have to act on these wishes or fantasies. At this age, boys experience more pressure than girls to adhere to gender-role expectations in areas such as choice of toys, hobbies, clothing, and hair styles. All my friends wear bras every day but I don't know if I am ready to wear a bra yet. If you have decided to wait, think about what you will say ahead of time if someone pressures you to have sex. In research studies, animals deficient in leptin did not undergo puberty, but puberty began when leptin was administered to the animals. If a child has the courage to ask this question, you should have the courage to answer it honestly. However, girls who have a later onset of menstruation after age 13 tend to have lower rates of regular ovulation in the years following the onset of menstruation.