Brown discharge four or five days after ovulation may be caused by low estrogen and luteal dysfunction. 1. Low estrogen: A transient drop in estrogen occurs when a woman ovulates, causing the endometrium to lose the support of estrogen, which results in a small amount of endometrial shedding and eventually a small amount of brown blood, which will return to normal after ovulation. 2. Luteal dysfunction: Luteal dysfunction belongs to ovarian dysfunction, luteal dysfunction will lead to a decline in female hormone levels, which in turn affects the transformation of the uterine lining, and there may be a small amount of brown blood secretion four or five days after the day of ovulation. Patients who have brown discharge four or five days after the day of ovulation can go to the hospital to clarify the cause of the disease and give treatment if necessary.