hello there Light brown odourless discharge which you have is premenstrual spotting. Spotting is mild bleeding that usual appears as a brown or pink stain on the underwear. It is not overt, bright red bleeding that occurs as in normal menses. Cervical erosion can lead to brownish discharge at any time not necessarily premenstrually. It also leads to bleeding during or after intercourse. Cervical erosions occur with genital infections. So you should consult a gynecologist. An erosion can be seen on internal examination itself and if present , repeat pap smear after course of antibiotics. Repeated Cervical erosions can be treated by cryotherapy which is a minor procedure involving freezing and thawing of eroded cervical tissue. Chronic cervical erosion can lead to cervical dysplasias and cancer so proper treatment and follow up is required if you have history of repeated erosions from past one year. Get annual pap smear if your previous was normal to rule out dysplastic changes in cervix. Its better to be aware and vigilant in follow up. So dont get tensed. Other causes of premenstual spotting can be: Low progesterone. Progesterone is the major hormone of the luteal phase. Insufficient levels are the major abnormality of the Luteal Phase Defect. Ovulation. There might be spotting or mild bleeding associated with the release of the egg. Also called mid cycle bleeding. This sort of spotting usually occurs early in the luteal phase, more than 8 days before menstrual bleeding Birth control methods. Most modern birth control methods use hormones which may affect the uterine lining and cause spotting or even bleeding. This sort of spotting is not limited to luteal phase. The kind of bleeding is usually called break through bleeding. Pregnancy. If pregnancy occurs after ovulation, there might be some spotting before the expected date of menses, which of course will be missed.This is called implantation bleeding. Pregnancy causes a one time premenstrual spotting and not a regular month-after-month spotting. An ectopic pregnancy is a serious possible cause of luteal phase spotting. Hormonal imbalance. Medical conditions such as thyroid disorders or medications such as aspirin may cause spotting. Genital diseases. Diseases such as fibroids, pelvic infections, ovarian cysts or genital tract cancer may produce spotting or bleeding. After Endometrial biopsy. This may leave a few months of premenstrual spotting on its wake. So i suggest you meet a gynecologist personally now if you have 2 or more episodes of spotting in 2 or more of your cycles before menses for proper evaluation. It is not wise to assume any cause before objective medical evaluation.. take care