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In my family, there are three September birthdays. My dad, my mom, and my grandpa – all within a week of each other.

But amongst friends, I know about seven people who were born in the month of September. It’s wild how many people seem to be born in September. But there might be a reason for it, according to research.

Photo: Max Pixel

Back in 2016, data journalist Matt Stiles decided to do some analysis of the number of births in the US according to day. So, he looked at data from 1994 through to 2014, and found that September seemed to be the month for birthdays to occur. In particular, September 9th seemed to be the most popular birthday overall, as it’s got an average of 12,301 births.

So, why is September such a high-volume time for births to occur?

Photo: Unsplash/Nick Stephenson

Well, if you flip the calendar back nine months, it’ll become a bit more apparent. It’s basic biology so to speak. A normal pregnancy lasts about 38-42 weeks, depending on how the mom and baby. Of course, the arrival of an infant is dependent on many other factors like is it your first pregnancy, etc. But, roughly speaking, a September birth is most likely a result of a December conception.

We all know that December is right in the middle of winter and holiday season. People are more likely to be spending their time indoors because of either the cold or just the festivities occurring.

Photo: Unsplash/Tom The Photographer

Besides the holiday parties happening with a little extra champagne, it’s also a very romantic time as a 2018 survey by Brides revealed that December is the most popular month for engagements to happen. In short, between the extra booze, the romantic nights in by the fire, the romance all around, we can totally understand why many people end up adding a limb to their family tree – whether accidental or intentional.

Of course, this is all just speculation, as are the hypotheses scientists have come up with to explain the high conception rates in December. Until concretely proven, some of these theories are just theories, such as the one that suggests sperm are less potent during the summer, or another theory that suggests a mother’s eggs or uterine lining is less receptive to sperm during summer.

Photo: Unsplash/freestocks

There are other theories that believe the shorter days of winter might possibly have something to do with how hormones function. Aaccording to Experian, there is another theory that believes people just see September as a better time to have kids since there aren’t any huge holidays happening and most people aren’t really taking vacations then, so you don’t really have to worry much about having a short-staffed hospital.

Regardless of the reason, September seems to remain a popular time for birthdays.