Most of the time, you can expect your first period about two to three years after you start to develop breasts. Most girls get their first menstrual period sometime between the ages of 9 and 16.

But don't worry — if you get it a little earlier or a little later, it doesn't mean there's something wrong with you. Every girl is an individual and develops at her own pace.

There are several things that can affect the onset of menstruation. One thing is genetics: The age when your mother had her first period may be a clue. Your weight may also have an effect. Athletic girls also tend to start menstruating later.

For the first year or two, your period will probably be irregular; it may not come at the same time every month. You can even have your first period and not have another one for months. But you should develop a regular period cycle within about two years of your first period. This irregularity can sometimes make you worry about spotting and leaking. Check out Always Thin Pantiliners. They are a great way to protect yourself against surprise periods.