How old are girls when they have their first period?

Answer 1

It can happen as young as age eight or nine, or as old as sixteen or seventeen. Although, these days girls typically begin menstruating (having their period) much earlier than they did even just a century ago or so. In the old days, girls normally didn't get their periods until they were in their late teens -- sixteen or so. I remember one of my high school teachers telling us that this is because in modern times, people are exposed to much more light. Even artificial light, apparently, helps children and teenagers grow and develop faster.