# Birthday frequency analysis **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [May 4, 2000, 7:28pm UTC](https://boards.straightdope.com/t/birthday-frequency-analysis/18592 "2000-05-04T19:28:29Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Earl\_Snake-Hips\_Tucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/earl_snake-hips_tucker/32/3269_2.png) [@Earl\_Snake-Hips\_Tucker](https://boards.straightdope.com/u/Earl_Snake-Hips_Tucker)\ **Post date:** [May 4, 2000, 7:28pm UTC](https://boards.straightdope.com/t/birthday-frequency-analysis/18592/1 "2000-05-04T19:28:29Z")
Folks, I do a lot of number-crunching where I work for performance and tuning, so I did a little free-lance number crunching on birthday statistics. Here is what I found: The highest frequency of births is from mid August thru mid October, the peak roughly being the month of September. The lowest frequency is from April thru early June, with the peak roughly being the month of May. This was a population sample of 900,000. Any comments on this analysis??? ---
**Author:** ![Earl\_Snake-Hips\_Tucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/earl_snake-hips_tucker/32/3269_2.png) [@Earl\_Snake-Hips\_Tucker](https://boards.straightdope.com/u/Earl_Snake-Hips_Tucker)\ **Post date:** [May 4, 2000, 7:31pm UTC](https://boards.straightdope.com/t/birthday-frequency-analysis/18592/2 "2000-05-04T19:31:18Z")
OK, by “peak” in the low frequency, I did actually mean the lowest spot. And there were 20% more births in the high month compared to the low month. ---
**Author:** ![lswote](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lswote/32/5737_2.png) [@lswote](https://boards.straightdope.com/u/lswote)\ **Post date:** [May 4, 2000, 7:36pm UTC](https://boards.straightdope.com/t/birthday-frequency-analysis/18592/3 "2000-05-04T19:36:28Z")
I commend your efforts but I think it is clear to see less babies are conceived in the summer than the winter which is pretty much an obvious conclusion since people are generally more housebound in the winter and have less extra-curricular activities. ---
**Author:** ![Mr.Cynical](https://avatars.discourse-cdn.com/v4/letter/m/ee59a6/32.png) [@Mr.Cynical](https://boards.straightdope.com/u/Mr.Cynical)\ **Post date:** [May 4, 2000, 7:37pm UTC](https://boards.straightdope.com/t/birthday-frequency-analysis/18592/4 "2000-05-04T19:37:28Z")
Are those numbers for the northern hemisphere only? I’d be curious to see if there’s an offset in the southern hemisphere. As for the August - October peak birth dates, it looks to me like people need a little something to keep them warm once the weather starts turning colder. You know, stay in bed, snuggle so on and so forth. ---
**Author:** ![Sue\_Duhnym](https://avatars.discourse-cdn.com/v4/letter/s/91b2a8/32.png) [@Sue\_Duhnym](https://boards.straightdope.com/u/Sue_Duhnym)\ **Post date:** [May 4, 2000, 8:15pm UTC](https://boards.straightdope.com/t/birthday-frequency-analysis/18592/5 "2000-05-04T20:15:48Z")
Well, my birthday is 9/12, but I was two weeks early. Conceived on New Year’s Eve. My hubby was also conceived on New Year’s but his DOB is 10/3. Lots of people getting laid for the holidays. ---
**Author:** ![Joe\_Cool](https://avatars.discourse-cdn.com/v4/letter/j/ecb155/32.png) [@Joe\_Cool](https://boards.straightdope.com/u/Joe_Cool)\ **Post date:** [May 4, 2000, 8:18pm UTC](https://boards.straightdope.com/t/birthday-frequency-analysis/18592/6 "2000-05-04T20:18:44Z")
I’m interested in seeing how many births occur approximately nine months after office Christmas parties. hehe ---
**Author:** ![brittainy](https://avatars.discourse-cdn.com/v4/letter/b/a88e4f/32.png) [@brittainy](https://boards.straightdope.com/u/brittainy)\ **Post date:** [May 4, 2000, 8:28pm UTC](https://boards.straightdope.com/t/birthday-frequency-analysis/18592/7 "2000-05-04T20:28:50Z")
My birthday is 9/12 too! ---
**Author:** ![UncleBeer](https://avatars.discourse-cdn.com/v4/letter/u/977dab/32.png) [@UncleBeer](https://boards.straightdope.com/u/UncleBeer)\ **Post date:** [May 4, 2000, 9:24pm UTC](https://boards.straightdope.com/t/birthday-frequency-analysis/18592/8 "2000-05-04T21:24:28Z")
Well, not to refute your data, but I checked the frequency of _my birthday_ and it seems to fall at the same time every year. Any one else care to substantiate this odd occurence? ---
**Author:** ![Mr.Cynical](https://avatars.discourse-cdn.com/v4/letter/m/ee59a6/32.png) [@Mr.Cynical](https://boards.straightdope.com/u/Mr.Cynical)\ **Post date:** [May 4, 2000, 10:02pm UTC](https://boards.straightdope.com/t/birthday-frequency-analysis/18592/9 "2000-05-04T22:02:10Z")
brittainy sez: > [@](#): > > \*\* > My birthday is 9/12 too! > \*\* Sue Duhnym sez: > [@](#): > > \*\* > Well, my birthday is 9/12, but I was two weeks early. > \*\* Sorry, brittainy and Sue Duhnym, but I’ll have to decuct points. You did not reduce to the lowest common denominator, which places your birthdays at 3/4. Please try harder next time. ---
**Author:** ![billehunt](https://avatars.discourse-cdn.com/v4/letter/b/c37758/32.png) [@billehunt](https://boards.straightdope.com/u/billehunt)\ **Post date:** [May 9, 2000, 12:51pm UTC](https://boards.straightdope.com/t/birthday-frequency-analysis/18592/10 "2000-05-09T12:51:38Z")
So, I’m guess-timating: the average was ~75k/mon high was ~82k/mon low was ~68k/mon high and low varying by about 9% above and below the mean. Doesn’t sound horrifically unbalanced. It would be interesting to know the number of pregnancies not carried to term. Perhaps there are more miscarriages during the winter for example. What sort of population was this? Were the years of birth close? For example, was this a group of college seniors? Or was this spread throughout many years? If the population was from one (or even a few) years, perhaps this is the impact of a localized event rather than a general rule. ---
**Author:** ![AWB](https://avatars.discourse-cdn.com/v4/letter/a/bb73d2/32.png) [@AWB](https://boards.straightdope.com/u/AWB)\ **Post date:** [May 9, 2000, 12:59pm UTC](https://boards.straightdope.com/t/birthday-frequency-analysis/18592/11 "2000-05-09T12:59:17Z")
My birthday frequency is once per year. It does vary a little, most times they are 365 days apart, but about every four years they’re 366 days apart. ---
**Author:** ![robinh](https://avatars.discourse-cdn.com/v4/letter/r/b77776/32.png) [@robinh](https://boards.straightdope.com/u/robinh)\ **Post date:** [May 9, 2000, 1:57pm UTC](https://boards.straightdope.com/t/birthday-frequency-analysis/18592/12 "2000-05-09T13:57:27Z")
Midwives and nurses I have spoken with put August as the busiest month here in the northeast US. Personal experience bears this out as well; the hospitals were much busier during my 2 summer births than for my spring and winter ones. Here’s a WAG: could there be a no-longer-necessary instinct to give birth close to harvest, when food is abundant? ---
**Author:** ![TwistofFate](https://avatars.discourse-cdn.com/v4/letter/t/cdc98d/32.png) [@TwistofFate](https://boards.straightdope.com/u/TwistofFate)\ **Post date:** [May 9, 2000, 2:38pm UTC](https://boards.straightdope.com/t/birthday-frequency-analysis/18592/13 "2000-05-09T14:38:00Z")
September… whole lot of Christmas Birthdays… just like me!!