San Bernardino County is moving up the list of places with the largest Latino populations in the nation.

The county had the seventh-highest number of Latino residents in 2007, up from ninth in 2000 and 13th in 1990, according to a report released Thursday.

San Bernardino County had 938,798 Latino residents last year, making up 47percent of the population, according to the Pew Hispanic Center’s analysis of U.S. Census data.

Nationally, Latinos accounted for half of the population growth since 2000.

"In a net sense, almost one out of every two additional residents since 2000 is Latino," said Richard Fry, the center’s senior research associate.

Between 2000 and 2007, the Latino population increased by 10.2million to 45.5 million. Latinos now comprise 15percent of the total U.S. population, according to the report.

In a change from the 1990s, the increase in the Latino population is due more to fertility than immigration, the report says.

Of the 10.2 million increase, about 60 percent was due to natural increase – births minus deaths – of existing residents while 40 percent was due to net international migration, the report says.

By contrast, 56 percent of the Latino population growth in the 1990s was the result of immigration and 44 percent was the product of natural increase.

"What we’re seeing is the secondary repercussions of the Hispanic migration of the ’80s and ’90s," Fry said. "Now, the fertility increase is driving Hispanic population growth."

Experts say Latino immigrants tend to have higher birthrates than second- or third-generation Latinos because they come to this country at a younger age when people start having families.

"Couple that with lower-than-average education and income rates, and the birthrate among the foreign-born segment is going to be larger than second- or third-generation Hispanics," said Adrian Pantoja, an associate professor of political studies at Pitzer College in Claremont. "As you move into the middle class and as economic mobility and education rates increase, birthrates tend to decline."

Latino advocates said the shifting growth trend isn’t surprising.

"Latino families tend to be larger than the average American family," said Emilio Amaya, who runs an immigrant assistance center in San Bernardino. "They have three or four kids, as opposed to one or two in the typical American family."

Increased border enforcement in recent years has slowed the pace of illegal immigration, he said.

"With so many restrictions, it’s becoming more and more difficult to enter without documents," Amaya said.

Opponents of illegal immigration criticized the report.

"Pew has again underestimated the impact of illegal immigration," said Rick Oltman, spokesman for Californians for Population Stabilization. "Is this just one more attempt by Pew to soften the impact of the obviously rising Hispanic population in the country to make it seem like it’s natural and legal, when in fact the majority is the result of illegal entries into the country?"

Oltman argues that much of the fertility-fueled population growth is due to so-called "anchor babies" – the U.S.-born children of illegal-immigrant mothers.

"I don’t believe those people should be put (into) the same category as Hispanic children born to Hispanic-American citizens or legal residents," Oltman said. "Even though anchor babies are given citizenship, they are the result of a failure to secure the border to stop illegal immigration."