The Rhogam shot can be administered into either a vein or a muscle. Most commonly, the shot is given in the buttocks or arm.
All women with Rh negative blood are advised to receive the Rhogam injection during the 28th week of pregnancy and again after giving birth. Because approximately 85 percent of all individuals are born with a positive Rh factor, the shot protects the mother from problems that can arise if the current baby or future babies are born with a blood type that is incomparable. A negative Rh factor indicates an individual's red blood cells do not contain the D antigen.