Unauthorized Immigrants and Their U.S.-Born Children.

An estimated 340,000 of the 4.3 million babies born in the United States in 2008 were the offspring of unauthorized immigrants, according to a new analysis of Census Bureau data by the Pew Hispanic Center.
Unauthorized immigrants comprise slightly more than 4% of the adult population of the U.S., but because they are relatively young and have high birthrates, their children make up a much larger share of both the newborn population (8%) and the child population (7% of those younger than age 18) in this country.
These figures are based on data from the U.S. Census Bureau’s March 2009 Current Population Survey, augmented with the Pew Hispanic Center’s analysis of the demographic characteristics of the unauthorized immigrant population using a "residual estimation methodology" it has employed for the past five years.
The new Pew Hispanic analysis finds that nearly four-in-five (79%) of the 5.1 million children (younger than age 18) of unauthorized immigrants were born in this country and therefore are U.S. citizens. In total, 4 million U.S.-born children of unauthorized immigrant parents resided in this country in 2009, alongside 1.1 million foreign-born children of unauthorized immigrant parents.

Complete Report:  (pewhispanic.org/files/reports/125.pdf ).