Not in these historical U.S. records. October 18 sits near the middle of the 366-date ranking. It ranks #164 of 366 dates by total births from 1994 through 2014. Rank #1 means most common.
October 18 had 235,107 births across 21 occurrences, or 11,196 births per occurrence. That is 0.274% of the 85,712,738-birth sample, or about 1 in 365 recorded births.
Within October, October 18 ranks #16 of 31 dates.
Does October 18 differ from nearby same-weekday dates?
October 18 has slightly fewer births than its controls in every planned comparison. In SSA 2000–2014, the primary comparison gives -1.5%. The planned comparisons range from -0.8% to -2.3%.
The 7-day comparison differs by less than 1%, so we treat the result as weak.
In the primary comparison, October 18 was above its controls in two years and below them in thirteen.
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 October 18 with controls from the same year.
| Comparison | Years | Control observations | Difference |
|---|---|---|---|
| 7 and 14 days, holidays excluded (primary) | 15 | 58 | -1.5% |
| 7 days only | 15 | 28 | -0.8% |
| 14 days only | 15 | 30 | -2.3% |
| 7 and 14 days, no holiday exclusions | 15 | 60 | -1.4% |
How were the comparison dates chosen?
The primary controls are October 4, October 11, October 25, and November 1 in the same year. Each is 7 or 14 days from October 18, so it falls on the same weekday.
In some years, a planned control falls on Columbus Day. We remove that control under the standard observed federal holiday rules. The year keeps its other controls.
By five-year period, the primary differences are -1.6% for 2000–2004, -0.9% for 2005–2009, and -2.1% 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.
Does the October 18 rank change over time?
Yes. We ranked 365 recurring dates by SSA births in each five-year period. October 18 placed #111 in 2000–2004, #261 in 2005–2009, and #75 in 2010–2014. The three ranks span 186 places.
The median span for all 365 recurring dates is 159 places. This span is above that median.
Each period has only five occurrences of October 18. It fell on a weekend twice in 2005–2009 and once in each other period. The period with more weekend occurrences has the less common rank.
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 October guide for the full month ranking. Compare the nearby October 13 and October 31 studies.
The methodology explains ranks and shares. Use the birthday checker to compare another date.