Of the people with Down syndrome in the United States: 67% are non-Hispanic and White, 13% non-Hispanic and Black, 16% Hispanic, 3% Asian or Pacific Islander, and 1% American Indian or American Native.

Down syndrome (Trisomy 21) occurs in people of all ethnicities at relatively consistent biological rates; however, Hispanic/Latino populations often show the highest observed prevalence of Down syndrome births in the United States. According to the CDC and high-fidelity longitudinal studies, Hispanic women have approximately 11.8 to 12.2 Down syndrome births per 10,000 live births, compared to roughly 9.2 for non-Hispanic White populations and 7.3 for non-Hispanic Black populations. These differences are largely attributed to demographic factors rather than genetic predisposition; specifically, Hispanic mothers statistically have a higher rate of births at older maternal ages (over 35), which is the primary risk factor for Down syndrome. Globally, countries with higher birth rates and less access to prenatal screening (such as parts of South America or Southeast Asia) may report higher prevalence, but the underlying biological chance remains consistent across the human race when adjusted for the age of the mother at the time of conception.