Republicans are pushing for congressional hearings to consider changing the nation's 14th Amendment to deny children of illegal immigrants the automatic citizenship the Constitution guarantees. They say foreign-born women are taking advantage of a constitutional amendment meant to guarantee the rights of freed slaves, and paint a picture of pregnant women rushing across the border to give birth. A recent Pew Hispanic Center study shows 8 percent of the 4.3 million babies born in the US in 2008 had at least one illegal parent.

A closer examination of the issue shows that the trend is not as dramatic as some immigration opponents have claimed.

Most children of illegal immigrants are born to parents who have made the United States their home for years.

Out of 340,000 babies born to illegal immigrants in the United States in 2008, 85 percent of the parents had been in the country for more than a year, and more than half for at least five years, Jeffrey Passel, a senior demographer for Pew, told The Associated Press.