Serum level of immunoglobulin E during pregnancy - does offspring sex matter?
We assessed maternal serum levels of total immunoglobulin E (IgE) in the first, second and third trimester and changes in total IgE levels from first to third trimester in relation to offspring sex. Within a cohort of 29 948 pregnant women, 392 women without a history of pre-eclampsia and with a liveborn child were randomly selected. Information on offspring sex was obtained through linkage to the Medical Birth Registry of Norway. Blood samples from each trimester were analysed for total IgE concentration. Differences in mean levels according to offspring sex were estimated and changes in total IgE levels from first to third trimester were assessed. In all three trimesters there was a tendency of women carrying a male fetus to have a higher mean total IgE level, but significant statistical differences were not reached. The total IgE concentration decreased during pregnancy, but the decrement was less in women carrying a male fetus compared with those who carried a female fetus.