Hello dear
I understand your concern
Generally
pregnancy is not possible when unprotected sex was done in the safe period of cycle.
But it also depend on the length of the menstrual cycle.
If you have short cycle then pregnancy can be possible as sperm can live in the genital tract for 4-6 days and this time if ovulation occur, pregnancy can be possible.
Blood
HCG detect the pregnancy earliest 12-14 days after the sexual intercourse.
So you can go for blood HCG and otherwise wait for period to come.
If period will delay by the 8-10 days from the normal expected period date then go for pregnancy test and or blood HCG to confirm the pregnancy.
With in 72 hours of sex you can use
I pill to prevent the pregnancy.
No any food prevent the pregnancy.
If you will pregnant , then intrauterine pregnancy can be terminated by
abortion pill under the advise of gynecologist.
Hope this may help you
Contact HCM for further health query
Best regards
Dr. Sagar