The US birthrate plummeted last year to a record low, with the decline being led by immigrant women hit hard by the recession, according to a study released Thursday by the Pew Research Center.

The study concludes that economic factors are having a direct impact on the number of children born, a key indicator that the financial crisis is not abating for millions of working families.

From 2007 to 2010, the overall US birth rate, defined as the annual number of births per 1,000 women ages 15 to 44, declined by 8 percent. During these years, the birth rate for US-born women decreased by 6 percent. For immigrant women, however, the decline was dramatic, plunging by 14 percent over this period. For Mexican women, the rate dropped even more sharply—by 23 percent.

While final data for 2011 is not yet available, preliminary data from the National Center for Health Statistics shows that the overall birth rate for last year was 63.2 per 1,000 women of childbearing age, the lowest rate since at least 1920, when the first reliable statistics became available.

By contrast, in 1957, during the postwar Baby Boom years (1946-1964), the birth rate peaked at 122.7. After declining somewhat in the 1970s, the US birthrate remained generally steady, at 65 to 70 births per 1,000 women, before declining again after the beginning of the recession in 2007.

The total number of births, which had been rising since 2002, also fell sharply after 2007, when it stood at a record high of 4.32 million among all women in the US of childbearing age. This number has steadily fallen since 2007, to 4.24 million in 2008, 4.13 million in 2009, to about 4 million in 2010. According to preliminary data, this trend continued in 2011, when there were an estimated 3.95 million total births. During this period, the US population continued to grow.

In the period from 2007 to 2010, the number of total births declined by 7 percent. Among immigrant women, births dropped by 13 percent, while falling by 5 percent among US-born women. Despite this overall decline, births to foreign-born mothers accounted for 23 percent of all births in 2010, and the 87.8 percent birth rate for foreign-born women was nearly 50 percent higher than the birthrate for US-born women.

The Pew Research analysis showed that the fall in the number of births to immigrant women was not due to a change in the number of women of childbearing age among this group, but to changing behaviors. Another study by Pew, published on October 12, 2011, showed that the overall decline in births in the US has been closely tied to economic stress.

This study tracked birthrate trends calculated from data from the National Center for Health Statistics and the US Census Bureau, and analyzed them in relation to data tracked by the Bureau of Economic Analysis, the Bureau of Labor Statistics and RealtyTrac. These economic indicators included “per capita income, per capita gross domestic product, employment rate, unemployment rate, initial unemployment claims, and foreclosure rates.”

Data compiled by this study shows a statistically significant correlation between economic distress and declining birthrates between 2007 and 2009. Only North Dakota, which had a nation’s lowest jobless rate in 2008, at 3.1 percent, showed any increase in the birth rate from 2008 to 2009 (0.7 percent). All other states and Washington, DC, experienced either no change or declines over this period.

Those states hardest hit by the economic crisis showed the greatest declines in births. California’s birthrate fell from 73.83 in 2007 to 68.50 in 2009. In real numbers, births in the state dropped from 566,414 in 2007 to 527,011 in 2009. California has been devastated by unemployment and budget cuts, including to a wide range of social programs. The state is also home to a large population of Hispanic immigrants.

Other economically stressed states that saw large declines in birthrates from 2007 to 2009 included Arizona (80.90 to 71.50), Georgia (72.93 to 67.67), Idaho (82.97 to 77.44), Nevada (78.95 to 71.24), New Mexico (77.46 to 73.37), and Oregon (66.28 to 62.53).

The October 2011 Pew study showed that the sharp fertility declines in the US since 2007 have been closely tied to economic changes at the state level, including declines in per capita personal income, numbers of initial unemployment claims, and foreclosure rates.

At the national level, Hispanics have seen the largest declines in birthrates since the onset of the recession—a 6 percent drop from 2008 to 2009. This group has also been the hardest hit economically, with unemployment increasing by 2 percentage points from 2007 to 2008.

Hispanic households also saw a staggering 66 percent loss in median wealth from 2005 to 2009. This compares to a 53 percent loss of median wealth for black households and a 16 percent loss for white households.