I too have RH (O) negative. I was a baby myself having my first baby and I just followed doctor's orders and had my shots of rhogam. They told me it would prevent the disease that used to result in the "blue baby" death. In the past, mothers with this factor would have only one baby...their first. Subsequent babies would die. Sometimes transfusions were attempted, and I'm not sure how they worked.
They say we are approximately 15% of the population or less. The problem occurs when the father has positive blood, which the majority do. I tried to find a non-medical website with more info for you, this one doesn't look too bad...