Neighborhood and Individual-Level Risk Factors for Term Low Birth Weight: An Examination of Cross-Level Interactions in Los Angeles County, California

This paper examines the association between term low birth weight (TLBW) and individual-level exposure to NO2 and whether this association differs by neighborhood-level physical and social factors. Data consisted of birth records (n=97,200), measures of neighborhood-level social disadvantage, racial and ethnic segregation, and greenness. Unconditional logistic regressions revealed that exposure to high NO2 levels in the third trimester is compatible with a weak positive association with TLBW after adjusting for maternal age, birthplace, race/ethnicity, smoking; infant sex; parity; and prenatal care payment type (aOR= 1.02, 95%CI=0.95, 1.09). To examine the presence of interaction, the model was re-run for each neighborhood covariate to include a product term. Evidence of a negative interaction between NO2 and greenness was found. The odds of TLBW when NO2 is high and greenness is low was lower compared to when NO2 is low and greenness is high, corresponding to a point estimate of 1.00 (95%CI: 0.74 1.34) when exposure to high NO2 levels is stratified at low NDVI