Influence of maternal infections with viral agents or Toxoplasma gondii during pregnancy on fetal IgE production.

The importance of maternal infections with Toxoplasma gondii, cytomegalovirus (CMV), Parvovirus B19, respiratory syncytial virus (RSV), and influenza A and B on fetal IgE synthesis was studied in 153 pregnant women. No case of specific IgM activity or viral DNA in cord blood, indicating a congenital infection, was found. From gestational week 15 to delivery, maternal IgG-Ab seroconversion to Parvovirus B19, RSV, influenza A, or influenza B occurred in 47 women. At delivery, serologic signs of past infection with T. gondii were observed in 29 (19%) women, and the corresponding figure for CMV was 117 (77%). The number of women with positive IgG seroconversion during pregnancy or positive IgG-Ab activity toward the studied infectious agents at delivery did not differ significantly among infants with an increased (> or = 1.3 kU/l; n = 51) or with an undetectable (< 0.1 kU/l; n = 102) cord-blood IgE level. These results show that genetic and other environmental factors probably have a greater influence on fetal IgE synthesis than do maternal infections during pregnancy.