RESUMEN
Prenatal exposures are associated with childhood asthma, and risk may increase with simultaneous exposures. Pregnant women living in lower-income communities tend to have elevated exposures to a range of potential asthma risk factors, which may interact in complex ways. We examined the association between prenatal exposures and the risk of childhood asthma acute care clinical encounters (hospitalization, emergency department visit, observational stay) using conditional logistic regression with a multivariable smooth to model the interaction between continuous variables, adjusted for maternal characteristics, and stratified by sex. All births near the New Bedford Harbor (NBH) Superfund site (2000-2006) were followed through 2011 using the Massachusetts Pregnancy to Early Life Longitudinal data system to identify children ages 5-11 with asthma acute care clinical encounters (265 cases among 7,787 with follow-up). Hazard ratios (HRs) were higher for children living closer to the NBH with higher cord blood Pb levels than children living further away from the NBH with lower Pb levels (P<0.001). HRs were highest for girls (HR=4.17, 95% CI: 3.60, 4.82) compared to boys (HR=1.72, 95% CI: 1.46, 2.02). Our results suggest that prenatal Pb exposure in combination with residential proximity to the NBH is associated with childhood asthma acute care clinical encounters.