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If the semen/pre-cum came in direct contact with vagina during the intercourse, then chances of pregnancy cannot be ruled out (condoms are associated with failures). Sometimes periods can also be delayed due to various kinds of stress for upto 10 days. Wait and watch for your periods. If you suspect to be pregnant, look out for development of any other new symptoms that could be suggestive of early pregnancy. Visit your doctor/gynecologist for examination and blood tests to confirm/rule out pregnancy.
Take care.