Hi doctor i have had four miscarriage at 20weeks and i just got anti d injection will i still experience another miscarriage again?

If the miscarriages were related to Rh incompatibility (Rh positive fetus with a Rh negative mother), the anti-D antibodies will not prevent Rh disease in the next pregnancy. If the pregnancy is with an Rh negative fetus, there is no need for anti-D antibodies.

The anti-D injections will only protect you against one possible cause of another miscarriage. Since you have had four late in the pregnancy you need a complete evaluation to determine a cause so that a future pregnancy can be actively managed to try to prevent a recurrent loss and at least prolong it to viability.