Fast food consumption in pregnancy and subsequent asthma symptoms in young children.

BACKGROUND: Recent cross-sectional studies suggested children's current fast food consumption to be related to frequency of asthma and allergies. Maternal prenatal diet has been suspected to contribute to children's asthma and atopic disease risks. OBJECTIVES: We hypothesized that maternal fast food intake during pregnancy increases offspring's risk for asthmatic symptoms. METHODS: We conducted a population-based study of 1201 mother/child pairs in Los Angeles, California. Detailed information about prenatal fast food intake and other dietary, lifestyle/environmental factors, and pregnancy was collected shortly after birth; further data were retrieved from birth certificates. Using the International Study of Asthma and Allergies in Childhood core questions, asthma and rhinitis symptoms were assessed, and doctor's diagnoses were recorded in offspring 3.5 years after birth. Poisson regression with robust error variance using a log link function was used to estimate relative risks (RRs). Models were adjusted using covariates or propensity scores. RESULTS: Maternal prenatal fast food consumption related to increased relative risks of their children for severe, and current asthma symptoms (wheeze last 12 months combined with doctor's diagnosis) in a dose-dependent manner: 'once a month': RR: 0.99 (95% CI: 0.36, 2.75), 'once a week': 1.26 (0.47, 3.34); '3-4 days a week': 2.17 (0.77, 6.12); and 'every day' 4.46 (1.36 14.6) compared to 'never', adjusting for potential confounders (p for trend = 0.0025). There was also suggestion of increased risks for rhinitis symptoms. CONCLUSIONS: These findings suggest that in utero exposure to frequent fast food through maternal diet may be a risk factor for asthmatic symptoms in young children.