Not especially. May 25 is less common than most dates in these historical U.S. records, but it is not among the rarest. It ranks #304 of 366 dates by total births from 1994 through 2014. Rank #1 means most common.
May 25 had 228,090 births across 21 occurrences, or 10,861 births per occurrence. That is 0.266% of the 85,712,738-birth sample, or about 1 in 376 recorded births.
It ranks #23 of the 31 May dates.
Seven of its 21 occurrences fell on a Saturday or Sunday. The average across all dates is 6.0. Weekend days have fewer recorded births, so this calendar mix can lower its total. This comes from the calendar in these years, not from the date itself.
What happens when May 25 is Memorial Day?
May 25 was Memorial Day only once in SSA 2000–2014, in 2009. That year it had 35.4% fewer births than nearby same-weekday dates.
One occurrence cannot show a pattern. In the other 14 years, May 25 had 2.1% more births than its controls.
Across all 15 years, the primary comparison gives -0.7%. With only the 7-day or only the 14-day controls, the results are -1.2% and -0.1%.
Baseline ranks use historical U.S. CDC/NCHS and SSA records, 1994–2014. The percentage differences use SSA 2000–2014 alone. Each table row compares May 25 with controls from the same year.
| Comparison | Years | Control observations | Difference |
|---|---|---|---|
| 7 and 14 days, holidays excluded (primary) | 15 | 60 | -0.7% |
| 7 days only | 15 | 30 | -1.2% |
| 14 days only | 15 | 30 | -0.1% |
| 7 and 14 days, no holiday exclusions | 15 | 60 | -0.7% |
| Memorial Day years only | 1 | 4 | -35.4% |
| Other years only | 14 | 56 | +2.1% |
How were the comparison dates chosen?
The primary controls are May 11, May 18, June 1, and June 8 in the same year. Each is 7 or 14 days from May 25, so it falls on the same weekday.
None of these controls fell on an excluded holiday. We exclude holidays under the standard observed federal holiday rules. We also exclude Christmas Eve, December 26, and the Friday after Thanksgiving.
By five-year period, the primary differences are +1.9% for 2000–2004, -5.4% for 2005–2009, and +2.2% for 2010–2014.
To combine the years, we divide the summed target births by the summed annual control means. Then we subtract one and multiply by 100. The result is not an average of annual percentages.
Is the May 25 rank stable over time?
Yes. We ranked 365 recurring dates by SSA births in each five-year period. May 25 placed #241 in 2000–2004, #249 in 2005–2009, and #232 in 2010–2014. The three ranks span 17 places.
That span is narrow. The median span for all 365 recurring dates is 159 places.
These ranks use raw birth counts. The ranking-stability study also compares annual shares and weekday-relative scores for every date.
Sources and limits
Baseline totals and ranks use FiveThirtyEight’s pinned U.S. birth files. We use CDC/NCHS for 1994–1999 and SSA for 2000–2014, so no year comes from both sources. Annual comparisons use SSA alone.
The source series have different administrative coverage. These records do not describe worldwide births, everyone alive today, or current birth rates.
The daily totals do not record delivery methods or scheduling decisions. Weekday matching does not remove every seasonal difference. Federal holiday rules identify calendar dates, not hospital schedules.
Use the May guide for the full month ranking. See also the May 5 study.
The Memorial Day birth study follows every actual Memorial Day.
The methodology explains ranks and shares. Use the birthday checker to compare another date.