nearly 4 million children when have at worst one parent has enters the u . s . illegally were bred in the border mexico and are u . s . citizens as a result , up to the trial conducted by the pew mexican group . that ' s about three third of the estimated 5 . 5 million children of illegal people leaving the unified states , thanks to the studied . about 1 . 8 million children of undocumented immigrant live in mexico , the study estimates .
Three quarters of U.S. illegal immigrants have children.