ing the risk of preterm birth (Alexander and Kotelchuck, 2001; Lu and Halfon, 2003), it too seems an unlikely mediator of socioeconomic disparities in preterm birth. Bacterial vaginosis is more common among women of low SES (Hillier et al., 1995; Meis et al., 1995); however, clinical trials of screening and treatment have yielded conflicting results (Carey et al., 2000; McDonald et al., 2005). Finally, women of low SES women experience more stressful life events and more chronic stress (Lu et al., 2005; Peacock et al., 1995), which are linked to preterm birth.

Other behavioral and social differences between African American and white women have been evaluated as potential causes of the disparity in preterm birth rates. Proportionately fewer African American women smoke cigarettes (Beck et al., 2002; Lu et al., 2005) and their rate of use of drugs and alcohol is no higher than white women’s (Serdula et al., 1991). The effectiveness of prenatal care for preventing prematurity has yet to be conclusively demonstrated (Alexander and Kotelchuck, 2001; Lu and Halfon, 2003; CDC, 2005i). African American women are more likely than white women to experience infections, including bacterial vaginosis and sexually transmitted infections (Fiscella, 1995; Meis et al., 2000). However, the cause of this increased susceptibility to infections among pregnant African American women largely remains unknown, and treatment has yielded modest or no benefits (Carey et al., 2000; King, 2002; McDonald et al., 2005). Insofar as African American women may experience more stress in their daily lives than white women, it has been suggested that maternal stress may contribute to the disparities in the rates of preterm birth between African American and white women (James, 1993; Krieger, 2002; Lu and Chen, 2004). Although a woman’s genetic makeup undoubtedly plays a role in the pathogenesis of preterm birth, the potential genetic contribution to racial disparities in preterm birth is unknown (Cox et al., 2001; Hassan et al., 2003; Hoffman et al., 2002; Varner and Esplin, 2005).