Lack of anti-D in women at birth following antepartum immune globulin prophylaxis

Abstract

Antepartum prophylaxis using Rh immune globulin suppresses maternal immunization to transplacental transfer of Rh-positive fetal cells, and, theoretically, to be effective, anti-D should be detectable until birth. We used a sensitive gel technique to quantitatively detect the serum concentration of anti-D at birth in 150 women who had received 300 microg of Rh immune globulin at 28 weeks gestation. Our method, which was sensitive enough to detect 20-25 microg, the recommended residual amount at birth, was positive in only 21% total, and in only 13% of women at term. Fifty-seven percent of women with premature births had above the recommended level of anti-D.