people may be scheduling labor/C-sections for more convenient days.

Convenient for the doctor moreso than the mother/baby.

The fact that Christmas Day, New Year’s Day, the 13th of each month etc are uncommon tells me it’s more likely that planned c-sections are the reason. People want a valentines baby.

Also, can confirm that the date of conception would be 27 May. Source: that’s my dad’s birthday and both me and my sister were due on the 14th 💀💀💀

True, but labour* takes time, and it can be several days; and sex (I’m told) usually happens at night. So you’d expect a peak in the days after, which doesn’t really happen. 15th is still a bit above average, but the days that follow are back to being well below average.

I’d wager on it being a popular day for planned Caesarean deliveries. Valentines baby and all that.

EDIT: I worded this badly and wrongly. I probably should have written "establishing* labour takes time". Labour does not and should not take days, but inducing labour can take a while, and it can be days from attempts to establish labour to delivery.

I would say that time of year in general, between Thanksgiving and Christmas. My daughter was conceived in December. She was born Sept 2nd. Mine is Sept 25th. My parents were getting it on around the holidays

fun fact: conception on 2/14 would actually suggest birth around 11/7 https://americanpregnancy.org/resources/pregnancy-calculator/?conception=2023-02-14

I was confused too.

My even smaller data set has my birthday being very rare and December 25th being common.

But Christmas is an outlier based on planned C-sections. Variation is more from 10 to 12.7. Still not that small for a random dataset. But as someone mentioned, 15 years are not enough valid for this.

OP doesn't say if it's world wide.

OP said:

This data represents 4,153,303 US-born babies only between 2000 and 2014.

Top 10 Most Common: Sep 12 (0.307%) Sep 19 (0.306%), Sep 20 (0.302%), Dec 19 (0.300%), Sep 10 (0.300%), Dec 20 (0.299%),Sep 18 (0.299%), Aug 8 (0.299%), Sep 26 (0.299%), Sep 17 (0.298%)

Top 10 Least Common: Dec 25 (0.155%), Jan 1 (0.186%), Dec 24 (0.193%), Jul 4 (0.212%), Jan 2 (0.231%), Dec 26 (0.238%), Nov 23 (0.238%), Nov 25 (0.240%), Nov 27 (0.241%), Nov 24 (0.241%)

Data Source: Kaggle.com/datasets/ayessa/birthday

"The first baby can come at any time; after that they take nine months"

I once, completely innocently, asked my mom how long after they moved into the house was I born. I'd always known it was about the same time, but wasn't sure on the exact timing of everything.

She said, very quickly, "9 months".

Sigh... At least I don't have to wonder?

Wouldn't the rainy season vary depending on what part of the world you're from? The rainy season in India and China is kind of around June/July, so wouldn't that mean there would be more births in March/April?

Or, perhaps this is just US or European data.

Edit: Yes, a post lower down suggests that this is US data. I think you're right.

But the rainy season is different in different places and this chart is likely based on data from lots of different places.

I was two weeks late, and 40 + 2 comes out to...my dad's birthday.

That’s wild. I was born in 9/11 but before 2001 (go dox me with this info I guess) and I’ve never had it be a like weird or bad thing, just an “oh interesting” thing.

Lil twin tower birthday cakes with sparkler candles! :D

Inductions too. My wife had still not delivered after 41 weeks, so we had a last-minute induction scheduled in early September. Everything was booked except the evening of September 10th lol. Jokes on them though, the labor was 30 hours.

Just realised that I was born exactly 9 months after my mom's birthday.

I started to laugh, then remembered I was supposed to be due a month and a half later than I was born… so doing the math puts me, well, dad’s bday! Good grief.

Would be kind of an odd choice to multiply it by 4. Not only brings the total over 100 but there is also no logical reason to multiply it by 4 except to make the spread of the colors tighter

Can't have 2 disasters share the same day!

🎵 Ohh girl tonight we're gonna make love

You know how I know? Because it's Wednesday 🎵

This is what I was thinking, make two charts side by side.

Oh god your comment made me just realize that I (April bday) was probably conceived on my parents anniversary (in July)...

Reminds me of the sorry that more babies are born between 9am-5pm now than ever because doctors choose to induce earlier than to get called in at nature’s timing.

Not just c-sections, but inductions for natural birthing too. My son was born on 23rd of December because of the same reason, he was due on like 19th so the doctors suggested to induce to avoid giving birth on Christmas.

25th baby here. I can confirm the present thing., not to mention having a party any time around this period is hard, my birthday is mostly forgotten, even by my parents. I tried to make it Dec 1st for awhile but it really carries a not my "real" birthday type vibe for people.

I was born on the 26th. I never threw a birthday party as a kid because all my friends had no time

Christmas birthday here, the present thing is absolutely true. Growing up, I was always pretty annoyed at the whole thing. It always felt so unfair getting overshadowed by Christmas. As mentioned by others, one of the hardest things is trying to actually plan and have a birthday party. Obviously my whole family would get together for Christmas so that would serve as my birthday party each year, but I can only recall a small handful of times that my parents ever had an actual birthday party for me, attended by my friends. And even on those few occasions, it always had to be a few weeks before or after Christmas because of how busy people usually are with family plans around the holidays.

It made me pretty bitter about my birthday all the way until I became an adult and had a complete change in the way I view my birthday. For context, my extended family is very large, and so is my wife's. Between grandparents, aunts, uncles, cousins, parents, and siblings, there are typically 3 or 4 birthday parties A MONTH, many times celebrating more than one birthday at a time. With so many parties, and family spread across a couple states, obviously everyone can't make it to every single birthday party.

Except mine.

It took me way too long to realize how special it is that on MY birthday, EVERYONE gets together. I get to see each and every one of my family members, some for the first time since the previous year, especially if they live farther away. Between my mom's side, my dad's side, and both sides of my wife's family, Christmas Eve and Christmas are usually a nonstop marathon of Christmas parties and as exhausting as it can get, I now absolutely cherish the opportunity to spend that time with everyone.

In addition, trying to plan things as an adult and realizing how busy people's schedules are around that time of the year made me extremely thankful that my parents were able to put together even just a small handful of birthday parties for my friends to attend when I was a kid. And because I now fully understand how hard it is to plan stuff around Christmas, I'm now completely fine with celebrating with some of my friends, no matter the exact date. It doesn't feel any less special if it's not ON my actual birthday. It sounds cliche, but it really is the thought that counts.

To end on a wholesome story and likely the exact moment my attitude towards my birthday changed was a few years ago when I must have mentioned to my wife (girlfriend at the time) about how I didn't really enjoy Christmas because my birthday seems to always just be a second thought. Well, Christmas arrived, and we headed over to her grandparents' house where the entire family was getting together. She made sure we were the last to arrive and when we did, before there was any mention of Christmas this or Christmas that, they turned off the lights as we walked in, and brought out a giant birthday cake and sang me happy birthday. I, a grown man, literally cried.

it's been at least 8 years since I delivered a baby, but IIRC, the government lets a Jan 1 baby "count" toward the previous year - presumably to prevent hasty inductions.

of course, I just say, wouldn't this just move the same incentive/risk to 24 hours later? or maybe it takes the edge off that number due to confusion and other motivations.

I would guess scheduling c-sections around holidays. From my experience, they want to get patients out of hospital for holiday and my daughter was pulled forward a few days to make sure we were heading home by Christmas.

I’m due 12/27 and will def be inducing to get baby out before the year end.

100/365.25 = 0.274.

The highest value is only 12% over the average rate.

The lowest value though is only 57% of average. That’s a bit bonkers.

I hate when it doesn't say in the title or graphic that it's US data.

Ive created this analysis for a different country (still northern hemisphere) and posted it here couple years ago. But the dates are quite different compared to the US.

Birthdays in the Netherlands