Naturally occurring insulin autoantibodies in neonates of normal pregnancies and their relationship to insulinemia and birth weight

Abstract

OBJECTIVE: The objectives of this study were to determine whether insulin autoantibodies are present in umbilical cord blood from normal pregnancies, determine whether cord blood insulin autoantibody levels correlate with respective maternal levels at delivery, determine whether cord blood insulin autoantibody levels are related to cord blood or maternal insulin levels, and to determine what relationship neonatal birth weight has with either cord blood insulin autoantibody and insulin levels or maternal insulin autoantibody and insulin levels. STUDY DESIGN: Paired umbilical cord and maternal serum samples were taken from 70 normal subjects at delivery. Measurements of serum insulin autoantibody (competitive charcoal radiobinding assay) and insulin (radioimmune inhibition assay) levels were performed. Multiple linear regression analysis and paired t tests were used for data analyses. RESULTS: Neonatal insulin autoantibody levels (120 nU/ml) were more than two times higher than maternal levels (49 nU/ml) ( p < 0.001). No correlation was observed between neonatal and maternal insulin autoantibody levels ( r = 0.14, p = 0.25). A positive correlation of both neonatal and maternal insulin with birth weight was observed ( r = 0.28, p < 0.02; and r = 0.36, p < 0.01, respectively). CONCLUSIONS: These results suggest that the insulin autoantibody levels in fetal cord blood are not related to maternal levels in normal uncomplicated pregnancies. In addition, insulin levels in both maternal and neonatal circulations were positively correlated with increased birth weight in the normal pregnancies studied.