Why do I only get small amounts of dark brownish blood instead of a regular period?

Why do I only get small amounts of dark brownish blood instead of a regular period? I am on birth control and there is no chance of pregnancy. I have always had an irregular period and terrible cramps which is why I'm on birth control. I've been on it for a year now. The first few months it was regular, but not anymore. For some reason I have always thought that whatever this issue is may affect my fertility one day. Any knowledge on my symptoms would be appreciated.

[Dr. Kokil Mathur]

Hi! Continued use of oral contraceptive can change your menstrual cycle, and cause it to even decrease and stop. It can change its color too. Take a pregnancy test. If the test is negative then other causes have to be looked at. Other causes of brownish discharge are hypothyroidism, cervical dysplasia, cervical polyps, cervicitis, vaginitis, cervical and uterine cancer, uterine fibroids, hormonal imbalance, genital ulcers, STDs and stress. You can discuss these possibilities with your gynecologist as on net and without examining it is difficult to give a confirmed opinion. A PAP smear and a STD panel must be done too along with a pregnancy test. Take care!