For most pre-teen girls, this is a major source of mystery and concern. Yet, even though pre-teens are very curious and concerned about when their period is going to start, pre-teens are reluctant to talk about it because they get embarrassed easily. As a school nurse, I have had many discussions with students about menstruation. Sometimes, a girl will start her period at school and not know what is happening. This is unfortunate because girls who don't understand what menstruation is become very frightened to have a bloody discharge on their panties, especially at school! Menstruation usually starts at age 12 but can begin as early as age 8 and as late as age 16. Parents should begin talking to their daughters about what they can expect with menstruation as soon as possible and not all at once. Too much information can be overwhelming for a preteen. No one can predict exactly when a girl's menstrual cycle will begin. Girls can suspect menstruation will begin about 2 years after breast development begins. For about a year before menstruation begins, most girls experience a white or clear discharge from their vagina before any bleeding from the vagina occurs. Some girls may have some cramping in their lower belly off and on for a few months before menstrual bleeding occurs. Most girls have irregular periods for the first year of menstruation. Menstruation means a girl’s body is getting ready to have children. The menstrual cycle typically lasts 28 days and menstrual bleeding usually lasts from 2 days to a week. Some girls worry because they are starting their period at different times from their friends or their periods are different. It is normal to be different from your friends, even though it feels scary sometimes.