Differences in total and allergen specific IgE during pregnancy compared with 1 month and 1 year post partum

Background: Pregnancy alters the function of many body systems, including the immune system. However, little is known regarding the effect of pregnancy on maternal IgE levels or atopy. Objective: To determine whether pregnancy consistently influences serum levels of total or allergen specific: IgE. Methods: Blood samples were obtained from 764 women during the third trimester of pregnancy and I month post partum. A third sample was obtained from 106 of these women I year post partum. Samples were analyzed for total and specific IgE to 8 regionally common allergens using a commercially available system. Sensitization was defined as an allergen specific IgE level of 0.35 W of allergen per liter or higher to any allergen. Results: Total IgE increased significantly post partum, both at I month (40.36 vs 35.37 IU/mL intrapartum; P = .001) and at I year (44.97 vs 37.00 IU/mL intrapartum; P = .005). Allergen specific IgE decreased significantly at I month for cat, dog, ragweed, timothy grass, and egg (P = .001 to P = .02) but not for dust mite, cockroach, or Alternaria (P = .15 to P = .90). Similar patterns of change in total and specific IgE were seen at I year. However, on average, only 3.5% of participants changed sensitization status to the individual allergens studied during the I year of observation. Conclusions: Compared with intrapartum levels, total IgE levels increased significantly at I month and I year post partum. Conversely, at the same time points, IgE levels specific for common allergens significantly declined to most but not all allergens. Few women changed their sensitization status over I year. Ann Allergy Asthma Immunol. 2009; 103:342-347.