what is ur blood type? depending on ur blood type it could that i can't rememeber what type it is but if the mother has a certain type the body will atack a fetus like a foreign body everytime! but the shot makes it so this does not happen and u can have a healthy pregnancy. I know someone who has this i think it's a+ blood type! it is very rare that a fetus suvives this without the shot i know of one from years ago my friends older brother survived but he is sevearly handicapped.
Are you sure you are understanding them correctly? The only thing I can think of is that with IVF, they have you take an intra-muscular shot daily for 12 weeks, but after that you don't take it any more. But I don't know why they would do this if your pregnancy was natural.