Massey, Douglas S. “Dimensions of the New Immigration to the United States and the Prospects for Assimilation- JSTOR.” Annual Review of Sociology, 1981, Vol. 7 (1981), pp. 57-85, www.jstor.org/stable/pdf/2946022.pdf. 

Over the past few years, the amount of immigrants that have come into the United States has increased significantly and the amount of immigrants now in the country has hit a record high 8.8 Million immigrants from 1909-1990. These immigrants have now settled very quickly into communities and made the cultural background of the United States so much more diverse and interesting.

“However, among both Cubans and South and Central Americans,
even standardizing for social and economic differences, fertility remains
below that of native whites, suggesting an independent effect due to
ethnicity or minority status (Jaffe et al 1976; Gurak 1978)”