Immunoreactive insulin in amniotic fluid from Rh-immunized women.

Immunoreactive insulin was measured in amniotic fluid from Rh-immunized women (anti-D antibody). The degree of immunization was expressed by the spectrophotometric index of the amniotic fluid and by the capillary hemoglobin concentration of the newborn. Higher levels of insulin were found in amniotic fluid from severely Rh-immunized mothers than from non-immunized, and a correlation between the degree of immunization and insulin concentration was indicated. To our knowledge this has not previously been demonstrated, and may justify some new hypotheses concerning the pathogenesis of the observed higher frequency of hyperinsulinism in babies of Rh-immunized mothers.