Interleukin-10 Predicts Preterm Birth in Acculturated Hispanics

Preterm birth is a major cause of infant mortality and numerous long-term health conditions such as neurocognitive and pulmonary morbidities (Martin et al., 2007). In the United States, preterm birth occurs in 12% of live births (March of Dimes, 2010). Alarmingly, the overall rate of preterm birth has increased by approximately 30% over the last 3 decades (Martin et al., 2007). Preterm birth rates vary greatly among ethnicities. Environmental and behavioral disparities may also influence preterm birth rates (Institute of Medicine, 2007). For example, the rate of preterm birth in Hispanics in the United States is highly influenced by acculturation through exposure to and adoption of U.S. behaviors and cultural beliefs (Cabassa, 2003). Hispanic women of lower socioeconomic status have better health outcomes than non-Hispanic Whites with comparable socioeconomic status. Paradoxically, preterm birth rates increase in Hispanics with greater levels of acculturation. A current theory suggests that individuals who are acquiring these new behaviors or cultural beliefs show an increased risk for preterm birth (Zambrana, Scrimshaw, Collins, & Dunkel-Schetter, 1997). Additional evidence suggests that, compared to foreign-born Hispanics, U.S.-born Hispanics show greater signs of “weathering,” a rapid decline in reproductive health (Wildsmith, 2002). As the Hispanic population is a rapidly expanding segment of the U.S. population, the increases in preterm birth in acculturated Hispanics is a potentially serious and growing burden on the U.S. healthcare system. Empirical evidence suggests that preterm birth is a multifactorial phenomenon involving deleterious and protective factors (Challis et al., 2009; Lyon et al., 2010). In the case of Hispanics in the United States, acculturation increases their risk of preterm birth by decreasing the protective influence of progesterone (Ruiz et al., 2008). These findings have raised the question of whether the relationship between acculturation and preterm birth is mediated by additional biological pathways such as inflammation. Inflammation plays a prominent role in the length of gestation (Challis et al., 2009; Lyon et al., 2010). During pregnancy, the balance between the pro-inflammatory Th1 cytokines and the anti-inflammatory Th2 cytokines undergoes a shift resulting in a predominance of Th2-derived signaling pathways. This increased activity of Th2 cytokines coupled with decreased activity of Th1 cytokines is thought to provide a protective influence on the materno–fetal interface and to facilitate normal, healthy gestation. The effects of Th1 and Th2 pathways during pregnancy are differentially mediated through specific signaling molecules. For example, interleukin-10 (IL-10) is a specific Th2 cytokine that serves as a protective factor for preterm birth (Challis et al., 2009; Lyon et al., 2010). Investigators believe that the protective effects of Il-10 are similar to the effects of progesterone (Chaouat, Meliani, & Martal, 1995; Piccinni et al., 1995). In contrast, IL-1 and IL-6 are specific Th1 cytokines associated with an increased risk of preterm birth (Challis et al., 2009; Lyon et al., 2010). The purpose of the current study was to investigate the potential relationships among acculturation, preterm birth, the anti-inflammatory Th-2 cytokine IL-10, and the pro-inflammatory Th1 cytokines IL-1 and IL-6 (Figure 1). Figure 1 Schematic depicting the theoretical interaction among inflammation, acculturation, and preterm birth in Hispanic women living in the United States.