I was rh- my first pregnancy..

So with my first pregnancy I was RH- I had to have a shot while pregnant with my daughter and right after birth. From what I could understand is that the blood could attack the fetis and kill it. So being pregnant with baby number 2 I'm not sure how this works. My first appointment is in the 19th and so glad its the same doctor from my first pregnancy! Just sucks waiting and not knowing if I have to have the shot again.. Does any other mommas know anything about being RH- with one pregnancy and how it works with the next pregnancy??