Bleeding between menstrual periods is a common occurrence among women. Causes include hormonal surges and reductions, the use of certain medicines, pregnancy, injury, inflammation, cancer, certain forms of birth control, vaginal dryness and stress, according to About.com.
Women's reproductive health systems are complex, and small changes can cause bleeding. According to the University of Colorado OBGYN and Family Planning, hormonal changes are the most common cause of bleeding between periods. Age is a large determinant of between-period bleeding, or abnormal bleeding. Younger women experience irregular menstrual cycles, which cause confusion as to the date of the menstrual period. Menopause and pre-menopause also cause abnormal bleeding. These developmental stages come with extreme hormonal changes. Bleeding also occurs during the implantation of a zygote, according to Mayo Clinic. This is light bleeding up to two weeks after conception. Some women believe implantation bleeding to be abnormal bleeding or an irregular period.
Bleeding between periods is typically minimal, and heavy bleeding between periods requires an immediate visit to the doctor, according to the National Institute of Health. At the doctor's appointment, patients should discuss the severity of bleeding, the time within the cycle that the bleeding occurs, sexual activity, other physical symptoms, and any medicines or supplements currently under consumption.