CHICAGO -- Gene Hall gave birth Thursday morning to her third daughter, Kayla -- a baby that, when you do the math, was conceived in the aftermath of February's colossal blizzard.
"We were stuck in the house that week because of the snow, my husband and I and our kids, all homebound, playing games and watching movies," Hall, 32, of Chicago's Chatham neighborhood, said before the delivery. "When I look back now, I remember my husband and I got some good quality time together.
"We thought we were done having children. This snowstorm baby was a blessed surprise."
It's a surprise you might expect to be widespread. For decades, disruptive events like storms and power outages have been anecdotally linked to a spike in birth rates nine months later. Couples are stuck inside and bereft of distractions, and so, the theory goes, nature takes its amorous course.
The premise, however, is proving to be short on supporting evidence, at least where Chicago's blizzard babies are concerned. Cook County records actually showed a significant drop in live births compared to the same time period two years ago.
But settling the question definitively is a tough task. Carl Haub, a demographer with the Population Reference Bureau in Washington, D.C., said years of data must be gathered on either side of a single event to discern whether it was responsible for an elevated birth rate.
"You really have to see a spike and be able to demonstrate that that's not a normal spike," he said. "It's going to be up and down no matter what."
Mini-baby booms have been popularly associated with everything from calamities (floods, ice storms, terrorist attacks) to celebrations (the Olympics, the World Cup, the Super Bowl). But they have often been picked apart by skeptics wielding the tools of statistical analysis.
The most famous critique came in 1970, five years after a prolonged blackout in New York City supposedly produced a spike in births. Public health researcher J. Richard Udry looked at six years of data and declared that there had, in fact, been no increase attributable to the blackout.
"It is evidently pleasing to many people to (fantasize) that when people are trapped by some immobilizing event which deprives them of their usual activities, most will turn to copulation," he wrote.
Udry's finding is frequently viewed as the final word in "disaster babies" -- the popular debunking website Snopes.com cites it in declaring the phenomenon a myth -- but more contemporary research suggests there might be something to the idea.
A 2005 study of birth rates following the Oklahoma City bombing looked at 10 years of data and found that the counties closest to the site had indeed experienced higher than expected numbers of births after the attack.
The researchers concluded that couples, confronted with stark evidence of life's fragility, might have been motivated to reproduce to ensure that their genetic line would carry on. Or they might have responded to the horror with a "strengthening of their traditional values" -- namely, having children.
But perhaps the most intriguing evidence supporting the idea of disaster babies was published last year by Brigham Young University economist Richard Evans. He and his colleagues looked at hurricane-prone counties on the Atlantic and Gulf coasts and compared birth rates that came nine months after the announcement of impending storms.
They found that while the rates went up after the mildest expected disruption (a tropical storm watch) they went down after the most serious (a hurricane warning).
"For low-level catastrophes ... you're indoors. The electricity is out. You've got nothing else to do, so you have increased sexuality," Evans said. "But with something severe, you can't make babies if you're running for your life."
He said that for a blizzard, which he equated to a tropical storm watch, he would expect about a 2 percent bump in births -- a tot windfall that would come from people like Amanda Jurgovan.
She and her husband Eric had tried for more than three years to have their first child. She was closely charting her ovulation cycles, and all the signs were right when the blizzard struck. Being snowbound just clinched the deal, she said. Their daughter Mckenna was born on Oct. 13, two weeks early.
"When we found out we were pregnant, we looked back and we were like, 'Oh, we had a blizzard baby,' " said Jurgovan, 28, of Crystal Lake, Ill. "It was like it was meant to be. It was obvious when we conceived."