US Illegal Immigrants Are 4% Of US Population But Have 8% of Newborns

From Pew Research, "8% - U.S.-Born Children of Unauthorized Immigrants:"

...while a little more than 4% of the U.S. adult population is composed of unauthorized immigrants, their children make up 8% of newborn population. Additionally, 7% of the overall child population (those younger than age 18) in the U.S. are the children of unauthorized immigrants.

The entire article, "Unauthorized Immigrants and Their U.S.-Born Children" by Jeffrey S. Passel, Senior Demographer, and Paul Taylor, Director, Pew Hispanic Center is available here.