If i was intimate with a partner 3 days before her period, which i ejaculated inside her, are the chances of her pregnant slim to none?she was not on bc

NOT SLIM: Any unprotected sex may result in pregnancy. True, sexual intercourse closer to a menstrual cycle may decrease the chance of conception - there is always a possibility of pregnancy. A home pregnancy test will give you an answer.

Pregnancy slim: Assuming your partner has approximately 28-day menstrual cycles, unprotected intercourse 3 days before her period would be too far after the previous ovulation (hence the period) and too far from the next ovulation to achieve fertilization. Chance of pregnancy is slim to none. If avoiding pregnancy with unprotected intercourse, should avoid days #8-19 of the cycle (first day of period is day #1).