Anemia and Jaundice in a Newborn

Charles T. Quinn, MD, MS

Cincinnati Children's Hospital Medical Center

Copyright of the American Society of Hematology, 2006. ISSN: 1931-6860.

This case was reviewed and updated in June 2011 by The Teaching Cases Subcommittee.


The blood bank reports the presence of an anti-Fya antibody. Antibodies against Fya occur in 0.8/1000 samples from pregnant women. Among susceptible infants, the distribution of the severity of HDN due to anti-Fya antibodies is as follows:

  • 94% none or mild HDN
  • 2% moderate HDN
  • 4% severe HDN

HDN is a transient disease, because maternal antibody titers decline with time in the infant’s circulation. What is the approximate half-life of the maternal IgG anti-Fya antibody in this child’s circulation?

2-3 months
2-3 weeks
2-3 days
2-3 hours

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