Which birthdays became rarer, and which caught up?
- 6,254,878births, 1995–20043,653 days
- 6,288,211births, 2016–20253,653 days
- October 26largest rank gain#352 → #86
- April 10largest rank fall#99 → #354
A single validated ONS vintage of daily births covers two complete, well separated decades: 1995–2004 (6,254,878 births) and 2016–2025 (6,288,211 births). Every figure is a share: each date's births per occurrence against its own decade's average day, with 100 meaning an average day.
Index and share
The index compares a date with an average day in its own decade: 100 is average, 103 means three per cent above it. The share is the percentage of the decade's total births that fell on that date, so for a date that occurs every year it is near 0.27%, one date's worth of a 366-date calendar. February 29 is the exception: it occurs in only two or three years of a decade, so its share is roughly a quarter of that, and it is shown alongside the others as published. Rank is a position among 366 dates, and dates with the same per-occurrence figure share a rank. A date can gain rank while its own index barely moves, because rank also depends on what every other date did, so both columns are shown.
The dates that climbed
Ten largest rank gains, index then → now (100 = average day)
One line per date from its 1995–2004 index to its 2016–2025 index.
| Date | Rank then | Rank now | Index then → now | Index change | Share of decade now | |
|---|---|---|---|---|---|---|
| October 26 | #352 | #86 | 95.2 → 102.3 | +7.05 | 0.280% | |
| October 25 | #292 | #46 | 97.6 → 103.5 | +5.83 | 0.283% | |
| November 3 | #302 | #56 | 97.4 → 103.1 | +5.74 | 0.282% | |
| November 2 | #328 | #89 | 96.6 → 102.3 | +5.70 | 0.280% | |
| October 20 | #333 | #100 | 96.3 → 101.9 | +5.65 | 0.279% | |
| November 1 | #255 | #36 | 98.5 → 103.9 | +5.43 | 0.284% | |
| October 19 | #331 | #114 | 96.4 → 101.7 | +5.22 | 0.278% | |
| November 22 | #307 | #100 | 97.3 → 101.9 | +4.61 | 0.279% | |
| May 4 | #297 | #97 | 97.5 → 102.1 | +4.52 | 0.279% | |
| October 31 | #290 | #90 | 97.7 → 102.3 | +4.61 | 0.280% |
The dates that fell
Ten largest rank losses, index then → now (100 = average day)
One line per date from its 1995–2004 index to its 2016–2025 index.
| Date | Rank then | Rank now | Index then → now | Index change | Share of decade now | |
|---|---|---|---|---|---|---|
| April 10 | #99 | #354 | 101.6 → 95.2 | -6.37 | 0.261% | |
| December 17 | #112 | #355 | 101.4 → 95.1 | -6.29 | 0.260% | |
| May 1 | #80 | #320 | 102.3 → 97.1 | -5.22 | 0.266% | |
| May 14 | #47 | #276 | 103.8 → 98.0 | -5.73 | 0.268% | |
| July 2 | #21 | #236 | 105.2 → 98.9 | -6.29 | 0.271% | |
| August 20 | #56 | #263 | 103.3 → 98.4 | -4.90 | 0.269% | |
| December 18 | #43 | #249 | 103.9 → 98.6 | -5.27 | 0.270% | |
| April 23 | #115 | #319 | 101.3 → 97.1 | -4.20 | 0.266% | |
| March 27 | #111 | #312 | 101.4 → 97.3 | -4.12 | 0.266% | |
| June 25 | #31 | #231 | 104.5 → 99.0 | -5.46 | 0.271% |
What a moving rank shows
These are temporal associations in calendar data. A date moving up means its share of births rose relative to other dates in the same country. Weekday composition alone can do it: a decade in which a date falls on Saturday more often will look quieter, because weekend births are fewer where scheduled deliveries are common. Changes in induction and caesarean scheduling, bank-holiday dates and the calendar drift of Easter are all inside these numbers too.
Whether the calendar became more or less even is measurable: the standard deviation of the per-date index across the 365 dates that occur every year is 3.53 in 1995–2004 and 3.86 in 2016–2025, so on this measure the spread between dates is slightly wider in the later decade. Individual dates moved a long way between these two decades.
Explore the England & Wales calendar →
Sources, method and limits
Source: Office for National Statistics, births by day of occurrence, England & Wales, 1995–2025 (one vintage, released September 8, 2026). Complete years from this single vintage are used. 3,653 days in the first decade and 3,653 in the second. The series includes births to mothers usually resident elsewhere.
Every figure above comes from the administrative records named here, at the granularity those records publish: a day, a month or a year. Coverage and definitions differ between countries and eras, so two sources are combined only where their documentation states the windows are separate, and the page where that happens says so.
Full method, leap-day treatment and definitions.
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