However, as the occasion only comes around once every four years, it means that those born on February 29 miss out on birthdays. Here's what to know about being born on Leap Day. Do you know what age you would be if you were born on a leap day? What happens if you are born on a leap day? In the UK if you are born on a leap day, February 29, your birthday is typically seen as February 28 or March 1 on non-leap years.