Incidence of Rh Immunization

Without intervention, approximately 8% to 17% of mothers in Rh-incompatible pregnancies become immunized at delivery (postpartum) and another 1% to 2% become immunized during pregnancy (antepartum). Termination of pregnancy carries a risk of immunization of 3% to 6%. similar to the 2% to 5% incidence seen after amniocentesis or chorionic villus sampling. 1,3,7,8
As an example in USA, using a conservative estimate of approximately 10% chance of Rh immunization, approximately 45,000 women per year are potentially at risk of immunization each year (446,000 X 10%). 

INCIDENCE OF RH IMMUNIZATION IMAGE
 

 1    Rubin E, Farber JL. Developmental and genetic diseases. In:Rubin E, Farber JL, eds. Pathology. 2nd ed. Philadelphia, PA: J.B.Lippincott Company; 1994:255-8.
3    Turgeon ML. Hemolytic disease of the newborn. In: Turgeon ML, ed. Fundamentals of Immunohematology: Theory and Technique.Philadelphia, PA: Lea & Febiger; 1989: 321-43
7    Bowman JM. The prevention of Rh immunization. Transfus Med Rev.1988;2:129-150.
8.    Zoon KC. Dear Colleague Letter, Office of Health Affairs of the FDA,Washington, DC: 1996.