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The urine pregnancy tests done very early in pregnancy can fail to show you positive results as the kits are calibrated ones, so unless the hormone levels in urine reach a certain level, they do not show positive results. If you suspect chances of pregnancy (as suggested by your symptoms, or if periods do not start within 10 days of expected period dates), you should consider visiting your doctor 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. Drink plenty of water. Take adequate rest.
Take care.