44 The Risk of Atopic Dermatitis in Children Exposed to Pets During Pregnancy

BACKGROUND: Although the mechanism is uncertain, some studies have linked prenatal and early-life pet exposure to a decreased risk of atopic dermatitis (AD). METHODS: 675 participants in a southeast Michigan population-based birth cohort were evaluated at age 2 to 4 years. Based on medical history and examination, a study physician was asked to determine whether there was evidence of current AD or a past history consistent with AD. Information regarding the presence of indoor dogs or cats was prospectively collected from the participants’ mothers during pregnancy. RESULTS: Of 675 maternal-child pairs, 255 (37.7%) mothers reported living with a pet during pregnancy and 150 children (22%) were diagnosed with either current or prior atopic dermatitis by age 2 to 4 years. Compared to mothers not exposed to indoor pets during pregnancy, the risk of AD was lower among offspring of 255 mothers that lived with an indoor pet prenatally [OR = 0.6, 95% CI, (0.4-0.9), P = 0.01]. The lower risk was seen primarily among 137 mothers reporting indoor dogs only [OR = 0.5, (0.3, 0.8), P = 0.009] or 43 that had lived with both indoor cat(s) and dog(s) [OR = 0.4 (0.1, 1.0), P = 0.05]. There did not appear to be a similar effect among 75 mothers with cat only prenatal exposure [OR = 0.9 (0.5, 1.6), P = 0.79]. When analyses were restricted to the presence or absence of dog exposure (not considering cat co-exposure), offspring were also less likely to have had current or prior AD [OR 0.5(0.3, 0.8), P = 0.002]. Results of analyses further restricted to dog exposure and “current AD” (AD present at the 2–4 year evaluation) were similar [OR 0.5 (0.3, 0.9), P = 0.013]. These results were not substantially different in logistic regression models adjusting for the child's total IgE level or the presence of atopy as assessed by positive allergen-specific IgE tests or positive skin prick tests to a panel of common allergens. CONCLUSIONS: Prenatal dog exposure is associated with a lower risk of AD in young children. The mechanism(s) responsible for this relationship require further study.