I had the anti d injection with my first pregnancy after 2 miscarriages and everything was fine. now 5 weeks pregnant. do i need it again??

Very likely: When a woman's blood type is "rh negative" and the father's blood type is not known, a woman will receive Anti d after a miscarriage. She will also receive Anti d at 28 weeks of a viable pregnancy, because the risk for production of antibodies after 28 weeks increases and the shot will last until 40 weeks. The father is typically assumed to be "Rh positive" - because the doctor doesn't know better