Because spotting can be a sign of a serious problem, you should see your doctor if you have it. The U.S. National Library of Medicine lists these common causes of spotting between menstrual cycles:
- Cancer of the cervix, uterus or sometimes fallopian tubes.
- Side effect certain procedures, including a biopsy of the cervix or endometrial lining.
- A miscarriage, ectopic pregnancy, or other complication of pregnancy.
- Fibroids or polyps in the uterus.
- Fluctuating hormone levels.
- Use of an IUD.
- A vaginal injury.
- Starting or stopping birth control pills or other hormones, or using blood thinners.
- Stress, underactive thyroid, or postmenopausal vaginal dryness.