Antibody detection and identification must be completed prior to performing a titer. If a clinically significant antibody is present, then it will be titered in antenatal work-up. A rising titer of an antibody known to cause hemolytic disease of the newborn is more significant than a single assay. Phenotypic determination of the father's RBCs can be helpful.
Limitations: While correlation does exist between titer and severity of erythroblastosis, titers do not always reflect the condition of an unborn child. False-negatives and false-positives occur. Abnormal results may indicate the need for amniocentesis.