A person born on February 29 may be called a “leapling” or a “leaper”. In common years they usually celebrate their birthdays on February 28 or March 1. In some situations, March 1 is used as the birthday in a non-leap year since it is the day following February 28.
Technically, a leapling will have fewer birthday anniversaries than their age in years. This phenomenon is exploited when a person claims to be only a quarter of their actual age, by counting their leap-year birthday anniversaries only. In Gilbert and Sullivan’s 1879 comic opera The Pirates of Penzance, Frederic the pirate apprentice discovers that he is bound to serve the pirates until his 21st birthday rather than until his 21st year.
For legal purposes, legal birthdays depend on how local laws count time intervals.
From Wikipedia