Hispanics accounted for more than half the nation’s population growth since 2000, the Pew Hispanic Center reported Thursday, and with most of that growth coming from births rather than from immigration, higher educational attainment for Hispanics is expected in the long term.

“We’re seeing the secondary immigration impacts from the ’80s and the ’90s,” Pew senior research associate Richard Fry said in a conference call Thursday on the report.

The Hispanic population “is of sufficient size and maturity that the natural (increase) is driving Hispanic growth — less so than international migration,” Fry said.

The estimated Hispanic population grew to about 45.5 million in mid-2007, or about 15 percent of the nation’s total population.

During the 1990s, the report said, immigration accounted for 56 percent of the growth of the Hispanic population.

Between 2000 and mid-2007, the natural increase — births minus deaths — accounted for 60 percent of the total Hispanic growth. During that time, the nation’s Hispanic population grew by 10.2 million. That represented 50.5 percent of the overall population growth.

Fry said in the news conference that the “Hispanic baby boom” likely would have positive effects down the road on educational achievements by Hispanics.

Now, according to a recent report from the American Council on Education, Hispanics in general have the lowest high-school completion rates (68 percent), and the lowest college enrollment rate (25 percent) and undergraduate degree attainment (10 per 100 enrolled) of any other ethnic group.

“On average, Hispanics that are U.S.-born tend to do much better in terms of basic schooling measures than are Hispanics that are born outside the United States,” Fry said.

“They’re exposed more to English … They graduate high school at higher rates. They’re more likely to go on to college. They still do not do as well as their White counterparts …