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If the sexual intercourse was during your fertile days or closer to your ovulation time, chances of pregnancy are possible. If fertile mucus had been present, sperms can stay alive for 5-7 days. After ovulation, egg has only 24 hours to get fertilized. The urine pregnancy tests done very early in pregnancy can show you false negative results as the kits are calibrated ones, so unless the hormone levels in urine reach a certain level, they do not show positive results. Wait and watch for your periods. 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 pregnancy is suspected, visit 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).
Take care.