The aim of the present study was to investigate to which extent environmental influences like indoor renovation activities affect the immune system of mother and child during the gestation period. Within the LINA (Lifestyle and Environmental Factors and their Influence on Newborn Allergy risk) birth cohort study blood samples of mothers during pregnancy and cord blood samples were analyzed for concentrations of the Th1/Th2 cytokines IL-4, IL-5, IL-13, IFN-γ and IgE. Data on indoor renovation activities (painting, flooring and new furniture) were assessed with questionnaires. Data on cytokine blood concentrations and exposure variables were available for 422 mother/child pairs. Neonates, who were strongly affected by renovation activities (especially floor covering and new furniture) during pregnancy, had significantly higher concentrations of IL-4 and IL-5 in cord blood. Among the single activities, new furniture, particularly flake board, were associated with increased IL-4 levels. Elevated IL-4 levels were also observed in the cord blood of children whose mothers reported wall-to-wall carpeting. Among flooring, polyvinylchloride (PVC) showed the strongest effect with increased IL-5 concentrations. The Th1/Th2 imbalance towards Th2 at birth was related to allergic sensitization in children at the age of one. There were only few and negative associations between renovation activities and Th1/Th2 cytokine concentration in maternal blood. Our study shows that under similar exposure situations the fetal immune system is more susceptible to the influence of environmental factors, in particular renovation products (flake board, wall-to-wall carpets and PVC) compared to the maternal.