Incidence of Maternal Rh Immunization by ABO Compatible and Incompatible PregnanciesBr Med J 1969; 1 doi: https://doi.org/10.1136/bmj.1.5641.399 (Published 15 February 1969) Cite this as: Br Med J 1969;1:399
- W. Q. Ascari,
- P. Levine,
- W. Pollack
The incidence of maternal Rh immunization in Rh-negative women following a single ABO compatible Rh-positive pregnancy is about 17%. This incidence was determined by following Rh-negative women through two Rh-incompatible pregnancies and analysing their sera for anti-Rh at the time of delivery of their second observed pregnancy. Maternal Rh immunization occurs almost exclusively after delivery; however, antibodies may not be detectable in the absence of further antigenic stimulation.
The incidence of maternal Rh immunization when maternal-foetal ABO incompatibility is also present is 9–13% and 17% for group O and non-group O women respectively. This study emphasizes the need to offer Rh-immune prophylaxis to Rh-negative women having Rh-positive infants whether or not ABO incompatibility exists between the mother and infant.