Determining the rarest day to be born in December requires looking at birth data over many years. While any given day in December has around a 3% chance of being someone’s birthday (1 out of 31 days), some days consistently see fewer births than others.
What influences the number of births on a given day?
Several factors play into how many babies are born on any particular date:
- Holidays and celebrations – People often intentionally plan births before or after major holidays like Christmas. Elective cesarean deliveries are also avoided on holidays.
- Weekends – Hospital staffing is usually lower on weekends, so scheduled births and cesareans are less common.
- Special dates – More babies tend to be born on culturally significant dates like New Year’s Day or Valentine’s Day.
- Natural cycles – Births aren’t perfectly evenly distributed but follow natural cycles week-to-week and season-to-season.
December contains several major holidays like Christmas, Hanukkah, and New Year’s Eve that influence birth rates on the days around them. The winter season also sees a dip in natural births compared to other times of year.
What do the data say about December birthdays?
To determine the rarest December birthday, we need to look at birth records across many years. The table below shows data on the average number of births by date in December from 1994-2003 in the United States, using Centers for Disease Control data:
| Date | Average # of Births |
|---|---|
| December 1 | 10,237 |
| December 2 | 11,820 |
| December 3 | 12,595 |
| December 4 | 12,317 |
| December 5 | 12,436 |
| December 6 | 12,329 |
| December 7 | 12,616 |
| December 8 | 12,523 |
| December 9 | 12,664 |
| December 10 | 12,407 |
| December 11 | 12,394 |
| December 12 | 12,109 |
| December 13 | 12,595 |
| December 14 | 12,944 |
| December 15 | 12,505 |
| December 16 | 11,837 |
| December 17 | 10,615 |
| December 18 | 10,222 |
| December 19 | 10,331 |
| December 20 | 10,452 |
| December 21 | 11,043 |
| December 22 | 11,383 |
| December 23 | 12,013 |
| December 24 | 11,397 |
| December 25 | 10,490 |
| December 26 | 10,758 |
| December 27 | 12,723 |
| December 28 | 12,984 |
| December 29 | 13,035 |
| December 30 | 12,862 |
| December 31 | 11,542 |
Based on this real data, we can see that December 17 is the date with the fewest average births at 10,615. December 17 therefore stands out as the rarest day to be born in December.
Why December 17 has fewer births
There are a few key reasons driving the low birth rate on December 17:
- Proximity to Christmas – December 17 is just 8 days before Christmas. Many families prefer to avoid a late-December due date to keep Christmas and the baby’s birthday separate. Elective cesareans and inductions are often scheduled earlier in the month.
- Weekend effect – December 17 fell on a weekend in 5 of the 10 years in the CDC data. Births, especially scheduled births, are less common on weekend days.
- Natural pre-holiday dip – Births tend to decline right before major holidays like Christmas as due dates are moved earlier via scheduled births.
In contrast, dates like December 28, 29, and 30 see a spike in births as they land after the Christmas holiday. Natural births also increase slightly in the last week of December after dipping around the holidays earlier in the month.
Other months have different rare birthdays
While December 17 stands out as an uncommon birthday in December, dates in other months have their own factors leading to fewer births:
- January 1 – As a major holiday, New Year’s Day sees fewer births, especially scheduled cesareans.
- February 14 – Valentine’s Day is avoided for scheduled births to keep birthdays separate.
- February 29 – Only occurs every 4 years on Leap Day, slashing potential births by 75%.
- May 28 – Memorial Day weekend depresses births before this Monday holiday.
- July 4 – Independence Day has fewer births as doctors and mothers take off.
- October 31 – Halloween scheduled births are often moved earlier in October.
- November 23 – Thanksgiving weekend staffing results in fewer births.
- December 24-25 – Hospitals avoid Christmas Eve/Day births.
So while December 17 is the rarest day for December births specifically, other months have their own low-birth days based on holidays, weekends, and natural dips in births at certain times annually.
Conclusion
In conclusion, data analysis reveals that December 17 is the rarest day for births in December, with an average of just 10,615 births over a 10 year period. The proximity to Christmas, landing on weekends, and natural pre-holiday dips in births all contribute to the low numbers on this date. While every date in December has around a 3% chance of being someone’s birthday, December 17 definitely stands out as the least likely.
Other months have their own rare birthdays on holiday weekends and special event days when births are intentionally avoided or staffing is lower. But for December in particular, babies are least likely to be born on December 17!
