It is not unusual for a female teen who plays sports to miss a period or have a light period. This may be due to the fact that her total body fat is decreasing as a result of her high level of activity. It would be helpful to make sure that your daughter is eating enough calories to keep up with all of the calories that she is burning from her activity.report abuse
There are other reasons that she may have a light or missed period, including thyroid disease or even pregnancy. For that reason, it might be a good idea to take your daughter to see her primary-care physician in order to address these issues.