A girl has to get used to the physical changes to her body. When her periods start she experiences bleeding from her vagina for about five days each month. This bleeding is known as menstruation and is caused by changes in her womb. During a period she must wear either an external pad or an internal tampon to absorb the blood. Many girls do not feel any ill effects during menstruation, but it is not uncommon for some to experience painful cramps and emotional upsets.
Boys often start the changes caused by puberty a year or two later than girls.
A boy's voice will become deeper, hair grows on his body and face and he will start to produce sperm. Adolescent girls and boys have a strong interest in their own sexual development and become more curious about the opposite sex. Becoming a woman Hormones cause a girl's body to develop into that of a woman. Her hips grow wider to make room for a baby to develop in her womb and to be born through her vagina. Breasts form that, after pregnancy, produce milk to feed the baby.