Everyone has a different blood type, either A, B, AB, or O, all pos or neg. It doesn't really mean anything but they need to know it because some types can only receive certain other types if you need to have a blood donation, or if you ever donate blood. Also your baby will get either the mother or the father's blood type, and if the baby has a different blood type than you than the doctor will give you a shot at some point just to make sure your body doesn't think the baby is a disease or something attacking it. My blood type is O+, I think maybe O+ is the kind that is considered the universal donator, as in every blood type would accept that if they needed a blood donation. Blood type is just something everyone has, it's like saying you have blue or green or brown eyes except that each kind doesn't always mix well with other kinds.