Hello dear I understand your concern You are on loestrin 20, birth control pill. It is highly effective in preventing pregnancy. It has just 0.5% failure rate. So chance of pregnancy is rare. Brown discharge could be a cervical mucus mixed with blood, hormonal imbalance, ovulation, premenstrual symptoms, side effect of pill. Brown discharge is not definitive sign of pregnancy. Absence period is most common and confirmatory symptoms of pregnancy. So if your period will delay by more than 7 days from your normal expected period date then go for urine pregnancy test and or blood HCG test to confirm pregnancy. Meanwhile avoid stress, take healthy diet, drink plenty of water, maintain proper pelvic hygiene and do regular exercise Hope this may help you Contact further if follow up needed Best regards Dr. Sagar