Prenatal and early-life exposure to indoor air-polluting factors and allergic sensitization at 2 years of age.

Background: Previous studies have suggested that exposures to indoor air-polluting factors during pregnancy and early life can influence childhood allergy development. These exposures have been investigated in singularity; however, the effect of simultaneous exposure to multiple factors remains unclear.

Objective: To evaluate the effect of prenatal and early-life exposure to 7 air-polluting factors on allergic sensitization at 2 years of age.

Methods: Mother-child pairs (n = 108) enrolled in the Kingston Allergy Birth Cohort were followed up from birth to 2 years of age. Exposure to air fresheners, candles, mold, cats, dogs, carpet, and environmental tobacco smoke (ETS) during the prenatal, 6-month, 1-year, and 2-year time points were obtained. A skin prick test (SPT) was performed on both the mother and the 2-year-old child.

Results: Exposure to candles during the prenatal window, cats during the 6-month window, and ETS at 2 years significantly increased the odds ratio (OR) of a positive SPT result (candles: OR, 5.096; 95% CI, 1.69-13.86; P = .006; cat: OR, 4.267; 95% CI, 1.096-15.68; P = .048; and ETS: OR, 3.78; 95% CI, 1.189-11.18; P = .04). Children with a positive SPT result had significantly more exposures than SPT-negative children (prenatal P = .005, 1-year P = .03, and 2-year P = .008). As the total number of exposures increased, the percentage of SPT-positive children increased (prenatal P = .005, 1-year P = .03, and 2-year P = .01).

Conclusion: We have provided evidence supporting the role of the indoor environment on atopic disease development. The combined effect of multiple exposures may be more influential to allergy development than a single exposure.