Influence of sex and gestational age on cord blood IgE.

Cord blood IgE (CB-IgE) is widely used as a screening parameter for atopy. Therefore it is necessary to define the normal values accurately. In this study influence of sex and gestational age on CB-IgE is evaluated. 5,305 cord blood samples were analysed. Boys had a higher CB-IgE than girls (p less than 0.001). Using a cut-off value for normal of 2.4 micrograms/l, boys had significantly more abnormal values than girls (p = 0.0475). Using a lower cut-off value (2.16, 1.92, 1.68 micrograms/l) the difference became more significant (p = 0.0029, p = 0.0036 and p = 0.0019 respectively). Gestational age (in the range from 34-42 weeks of gestation) had no influence on the absolute CB-IgE concentration nor on the number of abnormal values. From this study we may conclude that, when CB-IgE is used in prediction and prevention programs for atopic disease, the sex of the newborn should be taken into consideration when evaluating the results, in particular when the cut-off limit is lowered. No correction needs to be made for gestational age if the baby is born after the 34th week of gestation.