A typical menstrual cycle is between 24 and 34 days long. However, some women have an even shorter cycle which can cause two periods in one month, according to the New York Times. While a short menstrual cycle can be completely normal for an individual woman, bleeding twice in one month can also be a signal of an underlying disorder; visiting the doctor to discuss any abnormal bleeding is advised.
Bleeding disorders, hormone disorders and uterine fibroids or polyps can all lead to excessive and irregular periods, according to the New York Times. While most conditions that lead to excessive bleeding are treatable, seeking treatment early is key to preventing complications. Women should take note of periods that are irregular and keep a record to share with a doctor to help determine the cause of irregular bleeding. Information the doctor might need includes the length of the periods and any additional occurrences such as clotting, heavy cramping or heavy bleeding.
When a girl first begins menstruating, she can also have irregular periods that can include two in one month and then skipping a month or two, according to TeensHealth. This can be completely normal as hormones adjust to menstruation. However, if the girl is sexually active, abnormal menstruation can also indicate the presence of sexually transmitted diseases.