Third, downward mobility was associ

Third, downward mobility was associated with increased risk of PTB for all groups, with the largest risk difference observed among African- American women. This finding supports a weathering effect, 9 the hypothesis that chronic exposure to neighbourhood stressors can take a physiological toll on the body. Such wear and tear over time can lead to accelerated ageing, especially among poor African- American women, which could contribute to higher rates of chronic health conditions as well as poor birth outcomes. 9 It should be noted that during the study period in California, 22%, 43%, and 52% of white, Latina, and African- American women in the sample,respectively, experienced downward mobility or remained in lifelong residential poverty, which is troubling considering that intergenerational mobility is a central tenet of the American Dream.