FIRST QUESTION!!

What is the percentage of getting pregnant off precum?


SECOND QUESTION!!

When i see when my due date is going to be, it says june 14, 2008.. i don't really know because i never payed attention to how many days in between my periods are, so i usually put 24 jus for a guess..

But when it says conception date an earlier date than what I KNOW the day what that i was "gone" in was at the end of the month of september. why are my calculations different than the doctors?