UCL News


Which date is the one most people have their birthdays on?

6 September 2006

The answer depends on where and when you were born, since, in populations, dates of birth reflect environmental, social, and economic differences.

Until the late 1970s the date of birth in England and Wales followed the European pattern, where more births occurred in early spring (corresponding to conceptions in summer) with a subsidiary peak in September (corresponding to conceptions around Christmas). From the early 1980s the number of births in Britain has followed the American pattern. …

Using daily birth counts for England and Wales between 1979 and 1996 it is possible to identify the most frequent specific birthdays by simply adding the number of births for each date over those 18 years. The five most frequent dates are September 21, 24, 25, 19 and 26; the five least frequent are December 26, 25, 24, 27 and January 1. There were 32% more births in the former five dates combined than in the five latter.

Dr Mario Cortina Borja, UCL Institute of Child Health, 'Notes & Queries', 'The Guardian'