In all other states, birth rates declined, said Gretchen Livingston, the lead author of the report. Arizona had the deepest decline in its birth rate, down by 7.2 percent.

It is not unusual for child bearing to fall in times of economic hardship. Birth rates dropped 26 percent in the decade that ended in 1936, Ms. Livingston said, during one of the greatest economic calamities in American history. But the rates later pick up. “What people seem to be doing is not so much deciding not to have children, but postponing until things start to recover,” she said.

She pointed to the difference in age groups as evidence: the only one whose birth rate rose was the 40- to 44-year-olds, who could not delay childbirth any longer. All other age groups’ rates fell.

Hispanics, who were particularly hard hit by the recession, saw the largest decline, with birth rates down 5.9 percent from 2008 to 2009. Rates dropped by 2.4 percent among black women and by 1.6 percent among white women, the report found.