Quoting Mary-anne Cooper:" you go by your last period date and go from their. "
Quoting Jas ♥:" Not that I know of. Sperm can live up to 5 days inside of a woman's body so due date according to date of intercourse is likely to not be accurate."
Quoting _ __:" Thanks! I calculated it off of 1 day after and 5 days after so I have a general idea now! My birthday is right in the middle of it, that's weird "