According to Healthline, spotting between periods is quite common. Although rarely cause for alarm, it can sometimes occur due to underlying medical conditions such as stress, hormonal imbalances, thyroid disorders, miscarriage, polycystic ovary syndrome, diabetes, uterine fibroids or polyps, endometriosis, ectopic pregnancy, bladder or vaginal infections, vaginal dryness or cancer of the cervix, vagina, uterus or ovaries. A woman should visit a doctor to assess any concerns.
WebMD notes that most women experience spotting occasionally during their lifetime and need not be concerned unless the bleeding is heavy and occurs frequently or lasts for more than three days. Young girls may spot before they have their first full period, and older women commonly spot at the onset of perimenopause.
Everyday Health notes that blood thinners and some forms of birth control may cause spotting. Women who are pregnant are urged to visit with a doctor as soon as possible after spotting is experienced to rule out any serious complications with the baby.
Healthline warns that spotting may necessitate emergency care if it's accompanied by other symptoms such as pain, fatigue, dizziness or fever, all of which are considered to be serious. A doctor can perform diagnostic tests to determine the cause of the bleeding and prescribe a treatment plan if necessary.