PHOENIX — Arizona women just aren’t having as many babies as they used to.

George Hammond, the director of the Economic and Business Research Center at the Eller College of Management at the University of Arizona, said Arizona births rose from 37,591 in 1970 to a high of 102,687 in 2007. But since then there been a sharp decline, with the number pegged at less than 81,000 last year.

But Hammond’s analysis of the data also discovered something else.

While birth rates among non-Hispanic women dropped 14% in the decade following 2007, the decline among Hispanics was three times as much.

All this comes as Arizona is close to the point where the only way the state will continue to grow is if people keep moving here: The net difference between births and deaths currently is only about 20,000 a year in a state of more than 7.1 million.

And Hammond warns that dependence on in-migration is risky and could change sharply, as it did during the recession when virtually no one moved into Arizona. That, in turn, would mean that lower birth rates — especially the drop among Hispanic women — would have a ripple effect, including fewer students in public schools, community colleges and state universities.

That also has implications for retailers who Hammond said won’t find quite the demand for youth-oriented products.

Hammond isn’t the only one who has been looking at the Hispanic birth rate.

Economist Tom Rex of the W.P. Carey School of Business at Arizona State University, said the decline in Arizona has been “more significant” than the rest of the nation. And the picture is even more complex than that.

“The Hispanic birth rate in Arizona prior to the last recession was unusually high,” Rex said, and not just relative to Hispanics elsewhere in the United States. He said Hispanic women in Arizona were giving birth at a higher rate than even women in Mexico.

Rex said he believes that precipitous drop in the Hispanic birth rate — from 78 per 1,000 women of childbearing age in 2007 to less than 46 by 2017 — probably brings the figure closer to what would be a normal level.

But Rex said he expects Hispanic birth rates in Arizona and the rest of the nation to continue to fall, though he said the non-Hispanic birth rates —  about 38 births per 1,000 women of childbearing age in 2017 — are unlikely to change.

All that leaves the question of why the sharp change in Hispanic birth rates.

Hammond blames much of it on the “economic shock” of the Great Recession.

“A lot of Hispanics left the state,” he said. Hammond said there was a sharp drop in things like construction employment which had employed a lot of Hispanic — and, in fact, many undocumented — workers.

But that’s just part of it.

“SB 1070 made Hispanics feel less welcome here,” Hammond said.

That 2010 law contained a variety of provisions designed to curb illegal immigration. And while many provisions eventually were struck down, it still requires police, when they suspect someone is in the country illegally, to inquire about their immigration status.

“There are suggestions that a lot of those Hispanics moved to Texas and to other states to pursue jobs in mining, other sectors that were growing more rapidly,” Hammond said.

More to the point, he said, is it appears it was the high birth rate Hispanics that were the most mobile, meaning younger families with more children.

That fits into Rex’s theories about why Hispanic birth rates in Arizona plummeted when the economy went south. He said that, in a way, they were particularly high to begin with.

“Arizona’s immigrants from Mexico were disproportionately poorly educated,” Rex said, not just relative to Mexican immigrants from other states but also to the native Mexican population.

“Push factors from Mexico were greater for those with limited skills or skills not requiring much education,” he explained. But that’s just part of it.

“Pull factors to Arizona were strong for the less, educated, given the state’s disproportionate need for workers in agriculture, tourism and construction,” Rex said.

And what makes all that important, he continued, is a simple matter of social demographics.

“Birth rates and educational attainment are inversely related,” Rex said. Put simply, those with less education tend to have more children.

That, in turn, fits into what Hammond said is the current — and lower — birth rate among Hispanics now than in the years before the recession, when many Hispanics here were new arrivals.

“They’re kind of second generation and they’re fully assimilated,” he said of the current Hispanic population, meaning they’re seeing the world in a way similar to the non-Hispanic population among whom the birth rate is also declining.