Hi,
Welcome to ehealthforum,
If you are having regular periods, and periodic ovulation, then the chances of pregnancy would depend on how close to your probable ovulation time (egg release from ovary) you have the unprotected intercourse. Sperms once released inside you can stay alive for 3-4 days and egg once released from ovary can stay alive for 6-7 days). Wait and watch for your next periods. Look out for development of any new symptom suggestive of early pregnancy. Visit your doctor/gynecologist for further evaluation and assistance if you do not get your periods or if you suspect to be pregnant.
Take care.