Some young women don't want babies. Some believe they can't afford them. (iStock)

Millennial women are the slowest to have kids of any generation in U.S. history, according to a new study from the Urban Institute. But don't blame increasingly popular fertility innovations like egg freezing. Career ambitions appear to play a lesser role in delaying parenthood than a sputtering economy, researchers said.

Between 2007 and 2012—just before and right after the recession—birth rates among American women in their twenties declined by 15 percent, the report found. Financial hardship “causes young women who aren’t worried about the biological clock to say, ‘Things are tough right now. Let me put this off because I can,’” said co-author Nan Astone, senior fellow at the Urban Institute.

Birth rates in the U.S. remained fairly stable from the eighties to the early aughts, she said, but began to dip by 2008—especially among women entering their prime childbearing years. By 2012, millennials reproduced at a pace that would lead to 948 births per 1,000 women—“by far the slowest pace of any generation,” the report said.

All races experienced a birth decline. Hispanics saw the largest: From 2007 or 2012, the rate dropped 26 percent (1,570 to 1,158).  The rate for African American women fell 14 percent in the same five year period (1,216 to 1,046) and 11 percent for white women (976 to 866).


Chart by the Urban Institute

The recession hit young adults particularly hard. College students graduated into a tougher job market. Many opted to live with their parents as rent prices increased across the country.

So, it’s not surprising millennials put baby dreams on hold. There’s precedent: “Previous historical low points for twenty-something fertility rates occurred in the early 1930s and late 1970s,” the Urban Institute paper noted, “and coincided with other times of economic stress.”

Marriage rates, meanwhile, have also dropped across racial groups. More than a quarter of never-married Americans, 25 to 34, report they haven’t gotten married because they’re not “financially prepared,” a recent Pew survey found.

For some, no ring means no babies. The lack of marital commitment drove a disproportionate fertility dip among young white woman, the researchers found:


Graphic by the Urban Institute

It’s too early to tell if millennials will have fewer children than generations past. Women born between 1980 and 2000 might catch up on childbearing in their thirties, Astone said.

One thing to watch, though, is how current birth trends may affect income inequality down the line. Among baby boomers and Gen Xers, trends in marriage and childbearing seemed to deepen differences between low and higher-income families.

“Family inequality increased as single parenthood increased among already disadvantaged groups… while more advantaged young adults postponed both childbearing and marriage,” researchers wrote. “Millennial fertility might be a continuation of the trend in family divergence, or it might start a return to earlier patterns of family formation.”