Poor Sleep Quality and Associated Inflammation Predict Preterm Birth: Heightened Risk among African Americans

Study Objectives: Poor sleep promotes inflammation. In turn, inflammation is a causal mechanism in term as well as preterm parturition. In the United States, a persistent racial disparity in preterm birth exists, with African Americans showing similar to 1.5 times greater risk. This study examined associations among sleep quality, serum proinflammatory cytokines, and length of gestation in a racially diverse sample of 138 pregnant women. Design: Observational. Measurements: Women completed the Pittsburgh Sleep Quality Index (PSQI) and other psychosocial and behavioral measures during midpregnancy. Serum levels of interleukin (IL)-6, IL-8, IL-1 beta, and tumor necrosis factor (TNF)-alpha were determined by high-sensitivity assays. Birth outcomes were determined via medical record review. Results: Among African American women (n = 79), shorter gestation was predicted by poorer overall sleep (r(s) = -0.35, P = 0.002) as well the following PSQI subscales: subjective sleep quality (r(s) = -0.34, P = 0.002), sleep latency (r(s) = -0.27, P = 0.02), and sleep efficiency (r(s) = -0.27, P = 0.02). African American women with poor sleep quality (PSQI > 5) had 10.2 times the odds of preterm birth compared to those with good sleep quality. In contrast, among European American women (n = 53), gestational length was not significantly predicted by sleep quality (Ps > 0.12). Bootstrapping analyses showed that, among African Americans, IL-8 significantly mediated the association between sleep quality and length of gestation (indirect effect estimate -0.029; 95% confidence interval -0.06, -0.002). Conclusions: The data provide novel evidence that African American women exhibit greater inflammation in response to sleep disturbance than European American women and these effects correspond with length of gestation. Racial differences in susceptibility to sleep induced immune dysregulation may contribute to marked racial disparities in preterm birth.