Consider it the cuffing season finale.
If Hallmark’s dominance on Christmas, a profusion of films from the early 2000s, and now, Netflix’s continued push into the realm of made-for-streaming rom-coms are to be believed, the holiday time is a time for love. Forget Valentine’s Day—late November through December may very well be the most romantic time of the year. And there’s one particularly compelling fact to back this up. According to data published by the New York Times in 2006, September 16 is the most popular birthday in the United States—a finding that The Atlantic resurfaced in 2012 to reveal something even more interesting: Christmas Eve is the most common conception date—and New Year’s Eve is up there, too.
Since then, the numbers have shifted ever so slightly (which doesn’t necessarily negate the evidence), but nine out of ten of the most popular birthdays fall in between September 9 and 20—which still means that the holiday season is a popular time for couples to consider expanding their families. So how exactly has a season that has its roots in religious celebration turned into a season for baby-making?
Why the holidays are a popular time to conceive, according to science:
There’s an evolutionary component to consider. According to Smithsonian magazine, birth seasonality is common among all living things—not just people, but plants, mammals, and the like. Factors like the length of the days and temperature can cause a shift in birth rates—which is why summer and early autumn are rife with birthdays: Conception is more common in fall and winter. However, the publication notes that there are countless other factors to consider, including the fact that over the past few decades, birth seasonality has been weakening. This could simply be because of the increased access to birth control, reproductive education, and the fact that we have technology that those in the 1800s, when researchers first started studying birth seasonality, couldn’t even begin to imagine.
There’s also a biological imperative. Research shows that sperm concentration is significantly higher in winter compared to all other seasons—so couples who are trying for a baby might simply have better odds of conception during the holiday season. Testosterone levels also fluctuate by season, and men experience higher levels in winter—which increases libido. The rest is simple: The more sex you’re having (without protection, that is), the more likely you are to conceive. Couples who want a wintertime conception can improve their odds through fertility tracking, via an app, which can tell them the optimal days to try for a baby.
If you’re not trying to get pregnant, it’s wise to recognize that these biological factors can increase your odds of conceiving—so ahead of the holidays, sort out your birth control of choice and stock up on condoms (you’ll want to be prepared when holiday party season rolls around).
Why the holidays are a popular time to conceive, according to culture:
There’s also another answer—at least if you’re on the sentimental side. The holiday season is a time where the value of family is especially stressed. Just think of all the songs about all the songs that proclaim that there’s no place like home for the holidays and all the social gatherings that are so common throughout the season. These short-term reminders of the value of familial bonds can very well be enough to spark the thought between a couple to get started on making their own family.
Though we may think of ourselves as highly evolved, there is something about shorter days, colder temperatures, and ritualistic holidays that can bring out more evolutionary behaviors. Of course, we now have Netflix queues that can go on for days and days. But cuffing season remains at the top of mind for many singles once the first few leaves start to fall in autumn. There’s just something about the cold weather that makes us want to shack up with someone—consider it the inverse of hot girl summer. You can very well consider Christmastime the finale of cuffing season: The ideal time to lock it down with someone ahead of the New Year and, soon enough, Valentine’s Day.
The celebration of the family during the winter holidays can be enough to put life into perspective to such a degree, that you decide that now is the time for you to bring a new life into the world yourself. But those hot toddies, screenings of The Holiday, and Mariah Carey’s ever-classic, an ever-chart-topping declaration that Christmas is for lovers, most likely play a powerful role, too.