are ALL girl's nighties polyester??

[bumpbumpbump]

Why are girls pyjamas available in cotton but every nightie I've seen is polyester?
I know Boden do cotton nighties, but I was hoping to find some a bit cheaper.
Anyone come across reasonably priced cotton ones... have tried Next, M&S, Vertbaudet, Redoute, etc.

We found some nice cotton pyjama's very cheap at "Ethel Austin". They last so you can pass them on to a younger child too!