Sudden unexpected infant death, which includes death from Sudden Infant Death Syndrome (SIDS) as well as death from suffocation or strangulation due to unsafe sleeping areas, has decreased overall since the Back to Sleep campaign, but have not fallen overall since the 2000s. When examining specific groups, however, there were statistically significant declines in sudden unexpected infant death for non-Hispanic black, Hispanic, and Asians/Pacific Islander infants. Notably, though, there are still major racial and ethnic disparities in rates of sudden unexpected infant death. A recent study demonstrated that American Indian, Alaskan Native, and non-Hispanic black infants have the highest rates of sudden infant death. Definitive reasons for these differences are unknown. Notably, the study examining rates of sudden infant death did not control for other factors that may partially explain the results such as breast-feeding patterns, socio-economic status, and/or pre- or postnatal exposure to tobacco or alcohol.
Read more about this study on NPR in an article by Katherine Hobson.