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What is the rarest day to be born in December?

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.


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!