This subject is now going to get interesting:
Hot Air » Pew: 8% of American births to illegals?: "With some conservatives broaching the possibility of a Constitutional amendment to modify the 14th Amendment to clarify birthright citizenship as requiring at least one parent to be either a citizen or a legal immigrant, a chorus of voices has insisted that the problem of anchor babies doesn’t exist anyway, at least not significantly enough to make it a focus of political action. However, the nonpartisan Pew Research Center claim that births from illegals amounts to 8% of all American births does tend to put the question in a whole new context:
One in twelve babies born in the U.S. in 2008 were the offspring of illegal"