In 2011, the Pew Research Center analyzed the fall in fertility by geography and found a strong link between falling fertility and economic malaise: the only state to show a slight increase in fertility between 2008 and 2009 was North Dakota, which had one of the lowest unemployment rates in the country.

The decline had been particularly pronounced for women who were among the hardest hit by the recession: young women and Hispanics. The data released on Friday showed that the fertility rate for both groups was still in decline, though the pace of the drop had slowed considerably.

Young Hispanics have experienced the largest decline, with the rate down by a third since 2007 among women ages 20 to 24, said Kenneth Johnson, a demographer at the University of New Hampshire.

But slightly older women, in their early 30s, saw an increase in their fertility rate in 2012, up from a flat rate in 2011 and a decline in 2010. Women in their early 40s were the only ones not to experience a decline in fertility during the economic downturn, as they did not have the time to delay childbearing.

“It seems like change is working its way backwards,” said Gretchen Livingston, a demographer at the Pew Research Center. “We are seeing the next youngest group dipping a toe in the water.”

It is still unclear if the recent decline in births will be made up by a surge in fertility over the next few years, as happened during the baby boom after World War II.

“A big question is what will happen to the 1.3 million forgone births?” Professor Johnson said. “Will women start to have these babies, or will the births never be made up?”