Brown spotting six to 12 days after ovulation is a common sign of implantation bleeding due to pregnancy, according to BabyMed. Occurring when a fertilized egg attaches to the uterine lining, implantation bleeding is one of the earliest signs of pregnancy and is characterized by light, brown or pink bleeding and mild cramping. If pregnancy is possible, take a pregnancy test three to four days after spotting begins.
If pregnancy is not possible, other causes for spotting include perimenopause, stopping and starting birth control pills, hormonal imbalance, uterine polyps, polycystic ovary syndrome, thyroid disorders or a change in the menstrual cycle due to physical or mental stress, according to Everyday Health. While spotting one month is not a cause for alarm, Everyday Health recommends consulting with a doctor if spotting becomes a regular occurrence each month. It is important to keep a record of spotting and any associated symptoms that occur along with it to help a doctor diagnose the cause of the spotting.
According to Everyday Health, spotting can vary considerably from pink to dark brown. However, spotting is not as heavy as a regular menstrual cycle. If spotting between periods becomes so heavy that it soaks through a menstrual pad or tampon in one to two hours, it is important to contact a doctor promptly, as this can be a sign of a more serious condition.