New Jersey mom Michelle Birnbaum celebrates her real birthday for only the eighth time today.
And the guest of honor at her party will be another very special birthday girl — her 4-year-old daughter, Rose, who remarkably beat the 2 million-to-1 odds and also was born on Feb. 29.
Birnbaum, 32, insisted that as delighted as she is to finally have a built-in party partner, she never planed to create two generations of Leap Year birthdays.
It just worked out that way.
She went into labor on Feb. 28, 2008, but Rose didn’t make her grand entrance for another 11 hours, as the calendar flipped to Feb. 29.
“It was just luck, all the stars lined up at the right time,” said Birnbaum, a lawyer for kids in child-welfare cases.
Having a Leap Day birthday was never an issue growing up, said Birnbaum, who lives in Saddle River.
The only real inconvenience, she said, is the occasional Web Site that doesn’t recognize Feb. 29 birthdays when she has to enter biographical data.
As a kid, Birnbaum said, birthdays were always a two-day treat, spanning Feb. 28 though March 1.
“I always felt it was something very fortunate,” Birnbaum said.
“Almost everyone remembered my birthday, even strangers. The checkout lady at the market was always saying ‘Happy birthday!’ [at the end of February].’’
Birnbaum hopes to use their Feb. 29 birthdays as a hook for science lessons, to help Rose learn about Earth’s annual trip around the sun that takes a little more than 365 days to complete.
“She’s really smart, so hopefully in the next two years or her next real birthday, she’ll be [learning the solar system],” Birnbaum said.
Rose was among 11,430 babies born in the United States on Feb. 29, 2008, according to the National Center of Health Statistics.
There were 3.61 million US births in all of 2008.
Mom Birnbuam was one of 4.24 million US babies born in 1980, but the NCHS had no readily available data to show how many came into the world on Feb. 29 that year.
Brushing aside huge variables such as seasonal birth rates, specific generational trends, and other man-made manipulations, the odds of a mom and child sharing Leap Day birthdays are 1 in 2.1 million, according to James Ennis, a professor at Tufts University.
The demographic expert wished the Birnbaums happy birthdays, but wasn’t that impressed with the statistical quirk.
“I think the quote came from Aristotle, that rare events happen regularly and the improbable is pretty probable,” he said.