Enlarge Family photo Chad and Barbie Soper hold their baby Cearra Nicole, who was born Oct. 10, 2010. Unlike many moms, Barbara Soper never gets her kids' birthdays confused. That's because her first was born on Aug, 8, 2008, her second on Sept. 9, 2009 and her most recent on Oct. 10, 2010. Yes, that's 8-8-08, 9-9-09 and 10-10-10. The Rockford, Mich., mom and husband Chad weren't thinking about dates when their children were born. Their doctor had to give drugs to start labor for the couple's first daughter, Chloe Corrin Soper, who was born full term on Aug. 8 at Spectrum Health's Butterworth Hospital in Grand Rapids, Mich. Their son was a surprise all around. "He wasn't a planned baby at all, he was a miracle," says Barbara Soper. He was due on Sept. 20, 2009, but because sister Chloe's birth had caused some hemorrhaging, their doctor, Andrew Van Slooten, suggested he come out a little early so he'd be smaller. Soper was started on drugs to induce labor on Sept. 8, but it took 24 hours before Cameron Dane Soper made his way into the world, arriving on 9-9-09. Soper says she and her husband had thought it would be "neat" if their third child was born on 10-10-10 but because her due date wasn't until Nov. 4, it seemed unlikely. But it ended up being "kind of a mandatory eviction," says Soper. She developed blood clots in her legs and three weeks before her due date doctors told her the baby needed to be delivered. The induction was begun on 10-9-10, but it wasn't until 6:53 on Sunday night, 10-10-10, that Cearra Nicole Soper arrived. Despite being three weeks early, "she's feeding well," says mom. "She's a trooper." While the dates might seem "incredibly rare," they're really not. Such a lineup can only happen in the first 12 years of the century and at least 10 months apart, says Shannon McWeeney, a professor of biostatistics at the Oregon Health Sciences University in Portland. "Given that the first birth occurred in that window, the probability is not as astronomical as you might be compelled to think," she says.In fact, it's not that high a number at all, says Philip Stark, a professor of statistics at the University of California, Berkeley. "The 'chance' you get depends on the assumptions you make," he says. One set of assumptions gives a chance of about 1 in 50 million. More realistic assumptions — including allowing at least 11 months between births — increases it to about 1 in 2,500. Since thousands of women in the United States had kids in 2008, 2009 and 2010, this suddenly seems a little less extraordinary. But humans "like to look for patterns, to make sense of things" he says.For the Sopers, three is simply their lucky number — "we don't have any more planned," says Barbara. Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more