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Pullout/withdrawal method is associated with highest failures since pre-cum/pre-ejaculatory fluid is known to contain sperms and no man can be 100% sure that pre-cum/pre-ejaculatory fluid did not leak out during vaginal penetration. If she was during her fertile days/closer to ovulation time at the time of sexual contact, she can be at risk of pregnancy. Wait and watch for her periods. She should visit her doctor/gynecologist for further evaluation if periods are missed or abnormal, or if she suspects chances of pregnancy. If pregnancy gets ruled out and if you intend to remain sexually active, you should consider getting her 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 if you are not ready for pregnancy. She should be in regular monitoring and follow-up with her treating doctor/gynecologist and report any new/abnormal symptoms immediately.
Take care.