If by "maternity" you mean pregnancy,
and not afterward, I have several rules
to avoid unpardonable cliché:

1. No touching the belly.

2. No gazes down at the belly.

3. No gazes off into the future.

4. No soft focus.

I just shot my wife through her pregnancy
and you can find the gallery here:

http://www.flickr.com/photos/sanders...7619413429032/