Hi,
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Many women experience brown spotting/discharge few days before actual periods. The discharge that you describe could indicate impending onset of periods. The brown periods/altered periods could also suggest chances of breakthrough bleeding, infection, hormonal changes, endometritis, PCOS, cervicitis, cervical dysplasia/erosion etc. intercourse just before or during periods/menstrual bleeding usually does not result in pregnancy. If the brown discharge occurred after few days of having ovulation/fruitful intercourse, it could also be suggestive of implantation bleeding. Wait and see if it develops/changes into your period/menstrual bleeding within a few days. Look out for development of any other new symptoms if pregnancy is suspected. If periods do not start within 10 days of expected period dates, or if you get abnormal periods, or if you suspect chances of pregnancy, consider visiting your doctor/gynecologist at the earliest for thorough examination (to confirm pregnancy related changes/signs in body) and blood/serum HCG level test (to confirm/rule out pregnancy accurately). Be in regular monitoring and follow-up with your treating doctor/gynecologist and report any new/abnormal symptoms immediately. Take adequate rest. Drink plenty of water. Maintain healthy diet.
Take care.