A short menstrual period of no longer than three days may indicate pregnancy if it is light and not part of the regular pattern of menstruation, according to Everyday Health. It may also indicate the beginning of puberty in young girls, an underlying medical condition or menopause.
Menstruation is the monthly shedding of the thick endometrial lining of the uterus after fertilization does not happen, explains Everyday Health. Normal menstruation differs from woman to woman and may run from three to seven days in a normal pattern. The menstrual cycle also differs and ranges between 28 and 35 days in a given month.