The surprising truth: you share your birthday with 20 million other people!
Have you ever noticed that your birthday falls on the same day as lots of other people, even celebrities? The day feels special to you, but numbers show it is not rare. If you were not born on 29 February, the odds that a stranger has your exact birthday are about 1 in 365, which equals 0.274 percent. Because more than 7.5 billion people live on Earth, over 20 million of them blow out candles on the same date you do.
People born on 29 February face far slimmer odds: 1 in 1,461 or 0.068 percent. That still adds up to about 5 million individuals around the world.
Some calendar days attract far more births than others. Social habits and the weather steer the pattern. In the United States, many couples marry in June - doctors see a wave of newborns the following February besides March. Long holidays or severe storms keep partners indoors and nine months later hospitals notice a bump in deliveries. Romantic days such as Valentine's Day and family gatherings such as Thanksgiving also show a small rise in conceptions. Then again, high stress or poor maternal health lowers the chance of pregnancy.
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The seasons leave a clear footprint. Research that started in the 1990s shows that in the Northern Hemisphere births climb from March through May and fall from October through December. A mother's age, schooling, marital status and income shift the counts as well.
A 2006 New York Times report that used Harvard data found that summer produces the most American babies or September 9 is the single busiest birth date. At the other end of the list sit 29 February and the major holidays - Christmas, Thanksgiving next to New Year - when births drop. Fresh studies repeat the same finding - early September still tops the chart every year.
