Menstruation (a period) is a sign that a girl's body is able to conceive a child. While one girl may be excited at the prospect of becoming a young woman, another may be fearful of her first period and its implication that her childhood is coming to an end. Some girls start to menstruate as young as age 10 while others don't get their first period until they are 15. A few predictable signs will let you know that menstruation is on the horizon.
It's impossible to predict exactly when a girl will get her first menstrual period. As a general rule, it usually begins about two years after her breasts begin to develop. The National Institutes of Health says that during the time leading up to menstruation, a girl will grow pubic, armpit and leg hair. Her hip size will also increase and she will get taller. Before a first period, a girl might feel bloated, and her breasts might feel sore or swollen. Some girls also experience headaches or acne breakouts.
About six months before the onset of menstruation, a girl may notice a greater amount of clear or white-colored vaginal discharge. This discharge is normal and is usually nothing to be concerned about unless it has a strong odor or causes vaginal itching.
One of the least pleasant and, unfortunately, common signs of an impending first period is cramping. The Mayo Clinic says lower abdominal cramping is common in girls when their periods begin. Menstrual cramps can be sharp and strong or dull and achy. In some cases, cramping finds its way to the lower back as well. A heating pad or over-the-counter pain reliever may diminish cramps.
A girl may find that her emotions are on a roller coaster in the days leading up to her first period. She may feel down in the dumps and more prone to crying. She may also become irritable and angry more easily than usual.