Cord blood IgE and month of birth.

If cord blood IgE is used to detect those predisposed to become allergic it is important to define appropriately the normal values for this measurement. A commonly cited cut off point is 1.0 IU/ml. We analysed 5353 cord blood samples for IgE by means of an enzyme linked immunosorbent assay. Descriptive statistics of the distribution curve of cord blood IgE concentrations showed that most normal values were well below the cut off value of 1.0 IU/ml and that most abnormal values were in the neighbourhood of 1.0 IU/ml. It seems advantageous, therefore, to lower the cut off value for cord blood IgE. When cord blood IgE was analysed according to the child's month of birth a significantly uneven distribution of abnormal cases of cord blood IgE concentrations over the year was found. The occurrence of an abnormal cord blood IgE concentration showed a significant cyclic trend, with a peak near the end of April and a trough in late October.