It is super popular, I work in a London hospital, there was a day I went round the postnatal ward and there were 8 Maia's though most spelled Maya but also a Maja and 2 Maia's and there was also a Mia.
It is a name that works in lots of cultures, is relatively on trend and is therefore very popular in London. It is on the way up too, if it wasn't for variant spellings it would be much higher in the popularity charts.