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If the girl was during her fertile days at time of sexual contact and if pre-cum (it is known to contain sperms in it) or semen has come in direct contact with vagina chances of pregnancy resulting are high. If you suspect direct contact with semen or pre-cum with vagina at any time during your sexual contact, (and if you are not ready for the pregnancy), she should have considered taking emergency contraception within 48 hours of the unprotected intercourse to prevent pregnancy. Wait and watch for her next periods. If you intend to remain sexually active, she should consider visiting her gynecologist to get started on suitable regular birth control measures to be protected (after her periods). She should be regular with birth control use as instructed. Avoid having unprotected sexual contact.
Take care.