It is.

Some doctors used to say that it wasn't (that both weren't actually) because of some remotely higher risk of certain things (expulsion and perforation) however they have determined that the risk really isn't that high, it was just a weird prejudice. And some don't like giving it to women not in a committed relationship because of the risk of std's.... so they just say no women who haven't had children. But that's silly because only condoms prevent std's.

Anyway, if you doc won't give it to you, find a different one! Most do nowadays.

I had it and I have no kids.

I know a lot of women who had mirena and never had kids. So yeah, you could still get it even though you never had children.