I have a negative blood group and you used to have this after delivery but in my last pregnancy I was offered it about 6 months pregnant they said it's a new idea you still have this after delivery only if the baby is positive blood group though if he was the same as you then you wouldn't need it
The negative rh-factor of mother can cause complications when the rh-factor of fetus is positive. In this condition first baby can survive. But second pregnancy will be terminated due to a problem called erythroblastis fetalis. There is an injection which is injected immediately after first delivery. I am not sure about this shot without delivery. Discus this with your doctor.