(CBS News) America's birth rate has fallen to the lowest number on record, according to a new report from the Pew Research Center.

The drop may be due in part to falling birthrates among foreign-born women who immigrate to the United States, according to the researchers.

Looking at U.S. census data along with CDC statistics that were collected from 1990 through 2010, the researchers found the U.S. birth rate declined 8 percent from 2007 to 2010, and now stands at 63.2 births per 1,000 women who are of childbearing age. That's the lowest number recorded since 1920 when reliable statistics were first kept.

The U.S. birth rate's peak was in 1957 during the "Baby Boom," reaching 122.7 births per 1,000 women -- almost double today's rate.

The birth rate had held steady at around 65 to 70 births per 1,000 women since the mid-1970s, but has been falling since 2007, likely due to the recession, according to the report.

Since 2007, the birth rate for U.S.-born women fell by 6 percent, and the rate for foreign-born women dropped 14 percent. For Mexican immigrants, the birth rate fell by a staggering 23 percent.

"Latinos have been hit particularly hard by the recession, and the downturn in births is especially sharp for immigrants," D'Vera Cohn, co-author of the Pew study, told The Wall Street Journal.

Despite the declines, the birth rate for foreign-born mothers (87.8 births per 1,000 women) was about 50 percent higher then the rate for women born in the United States (58.9 births per 1,000 women). The researchers say that's because immigrants are more likely than others to be in their childbearing years.

In 2011 there were an estimated 3.95 million births, down from 4 million the previous year.

The full report from Pew Research Center can be accessed on Pew's website.