If you had a baby yesterday, I hate to be the one to tell you this but your baby's birthday is not unique. In fact, it's the least unique birthday there is.

Zippia.com did a study of data from FiveThirtyEight.com, the CDC, and the Social Security Administration to find what the most popular birthdays are in the United States. They found that September 9th is the single most common birthday in the country.

September is also a really popular month for births. Nine of the top ten birthdays are all in the middle of September. The top ten are:

  1. September 9th
  2. September 19th
  3. September 12th
  4. September 17th
  5. September 10th
  6. July 7th
  7. September 20th
  8. September 15th
  9. September 16th
  10. September 18th

December, with lots of festive holiday cheer and parties, is apparently also a month when people get together in a more intimate manner. If you go to the middle of those September dates, roughly the 15th, and subtract the average 40 week gestation period for women to have a baby, that puts you on December 10th.

So September is the most popular time to have a baby while December is the most popular time to make a baby.

Growing up in a small town I was in a relatively small class. I graduated with only 44 other kids at Beresford High School. Four of those 45 kids had birthdays in the hot zone of September. One was the 16th, two were on the 17th, and one on the 18th.

What's even crazier is that December 25th, Christmas Day, is the least popular birthday, ranked 366th. That is 19 spots less popular than a day that only happens once every four years, February 29th. Leap Day is ranked 247.

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