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This week, several media outlets rediscovered an old New York Times chart that tells you how popular your birthday is, ranking each day of the year from 1 to 366. While it's fun to learn the most common birthdays in the U.S., it's much more fun to think about the most popular conception dates! As it turns out, they aren't at all random. The most common birthday in the United States, according to the Times data, is September 16, and the average pregnancy lasts 38 weeks, so using Discovery Health's handy conception calculator, we discovered that the most popular conception date is December 24! That's according to the typical method for estimating due dates anyway. But if the logic follows, more Americans fertilize an egg on Christmas Eve than on any other day of the year. (Disturbing news for those 9/16 babies who would prefer not to know that their parents probably created them in an in-law's guest bed.)  

But there's more: The third most popular birthday in America is September 23. Subtract the length of a pregnancy, and lo and behold, you get December 31 -- New Year's Eve! The third most popular conception date. Calculating conception dates is obviously tricky business because pregnancy lengths vary. But in general, when you consider that the top 10 most common birthdays all fall between September 9 (the second most popular, which would have a conception date of December 17) and September 24, it would seem that the holiday season is a busy, busy one for American parents-to-be.

Having uncovered this fun trend, we decided to calculate backward for a few other popularly celebrated holidays to see how common the resulting birthdays are. None of them turn out to be as sexy as the holiday season, but there are some surprising finds.

Are you a Fourth of July baby? Those conceived on July 4 are likely born on March 27. That's the 225th most popular birthday, so ... not that many people are getting it on for America's birthday.

Are you a Valentine's Day baby? Those conceived on February 14 would likely be born on November 7. That's the 236th most popular birthday so, oddly enough, not a very popular conception date, either.

Are you a Halloween baby? Those conceived on October 31 would likely be born on July 24. That's the 72 most popular birthday. It's not that popular, but still more common a conception date than Valentine's Day. Creepy? 

Are you a Thanksgiving baby? Hard to say because it isn't a fixed date. We left off other holidays for which this is true, but given its role in the triumvirate of occasions we (Christians, at least) celebrate during "The Holidays" it was worth investigating. Birthdays in mid to late August (that would result from a late November conception) range in popularity rankings from the 30s to the 80s, thus the Thanksgiving season is more popular than some other holidays, but it's got nothing on New Year's or Christmas.

So there you have it. By now you're probably deeply incurious, but compelled anyway, to calculate your own conception date, and we invite you to do so with the Discovery Health calculator. Where it says "estimated due date," just input your birthday and make sure to use 2013 if you weren't born in a leap year (and 2012 if you were.) When you do, be sure to consider non-national dates of note, like your father's birthday, or your parents' wedding anniversary. We apologize for sending you down this rather unpalatable road, but, if you're like us, the curiosity was just too much to bear. 

Image via Shutterstock by Carlosseller

This article is from the archive of our partner The Wire.