DH and I only used condoms for 5 or so yrs. i have only had one PG scare and I wasn't PG. One of my friends got PG in high school when her and her BF at the time had sex. She lost the baby very early tho. i know that doesn't help you but i think that as long as your DP knows how to use a condom properly then you should be fairly safe. if you are that concerned then you need to use a backup birth control or contraceptive.