Red cell autoantibody production in utero: a case report.

Background: Autoantibody production by the fetus is thought to be extremely unlikely. Only one possible case of in utero autoantibody production against red cells by the fetus has previously been described.
Study Design and Methods: A case of apparent red cell IgG autoantibody production in utero is reported.
Results: This was established by a positive direct antiglobulin test in a newborn infant without evidence of maternal alloantibodies or autoantibodies. There was no evidence of clinically significant hemolysis at the infant's birth. After 6 weeks, his direct antiglobulin test remained strongly positive. The infant thrived without evidence of hemolysis, and after 6 months the direct antiglobulin test was negative.
Conclusion: The production of autoantibodies to red cells in utero is possible, though rare. This did not result in apparent hemolysis in this patient.