What is the World's Most Common Birthday?

Do you share your birthday with many others?
Do you share your birthday with many others?

To everyone around the world, a birthday is a second chance at a New Year, albeit a more personal one. These days represent joy and happiness to most people while to others it comes with trepidation that they are aging. Regardless of the feeling on that day, there is no denying that it is a unique day. For this reason, most people usually prefer to be the only ones in their surroundings having a birthday on a certain day. In the name of science, experts started conducting researches into the most common birth date and month of the year.

The World's Most Common Birthday 

There have been a number of researches done in the past that shed some light on the matter. One such research used birth data for millions of people and established that the most common birthday is September 9th, especially in the US. On a more general note, September is the busiest month when it comes to birthdays. Researchers from Harvard University also did a study from 1973 to 1999 in order to determine the most common birthday. In those years, the research established that the busiest month when it comes to birthdays is September although the date was 16th and not the 9th. The September 9th figure was established using more recent data ranging from 1994 to 2014. The data for the newer study was supplied by the National Center for Health Statistics and the Social Security Administration.

The above data is only unique to the United States. Interestingly, however, data from around the world also shows a similar pattern although, aside from September, it also includes July and August as the busiest birth months. As one moves towards the lower latitudes, the peak birth months move towards later months of the year. For example, the tropical zone has the most birthdays in the months of September and November. In the Southern Hemisphere, the common birthday months shift to between March and May.

The Most Common Conception Month 

This research leads to extra questions about the most common month of conception. Based on a gestation period of 40 weeks, then the most common conception month in higher latitudes is October. Some of these countries include Russia, Denmark, and Finland. For most countries, however, the most common conception month is December. Some of these countries include the United Kingdom, the United States, and Japan.


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