I had never known anyone named Mia or Myah until about a dozen years ago when every preschool class seemed to get at least a couple of girls with those names, though the spelling varied.
Boys names don't seem to follow fashion quite as much as girls' do. There are still lots of boys named Michael, Christopher, and John but masculine names do change with trends too. Often girls start getting named something that had formerly been used only for boys and after that fewer boys are given those names. Some examples are Corey, Kelly, Kimberly, Lindsey, Madison, Morgan, and Sidney.
Sometimes lots of babies are named after a famous person. When I was born there were very few girls in America named Janet, but a few years later Janet Leigh became a famous movie star and thousands of baby girls were given that name.
As a kid I wanted to be called Jenny, but my mother wouldn't allow it. She said everyone knew Jenny was a name for a mule, especially one that had been in the comic books back when Mom was younger. But 30 years ago Jennifer became one of the most popular names for girls. I guess by then everyone had forgotten about the famous cartoon mule. Very few boys are named Donald today, and Mickey is seldom used as a nickname for Michael anymore, for obvious reasons. Fame can also be a deterrent to the use of certain names.