I sent off a journal paper for review back in February and I'd really like to chase it up now with the editors. Waiting to hear back this long is not unusual in social sciences, and people I have co-authored with have chased up articles but I have never done so myself. I am unsure of the protocol for doing this and what kind of message to send to the editor? I don't really want to sound unprofessional or give any easy excuses to have my paper rejected!
Anybody had any experiences in this?

I chase up editors after 3 weeks or so in science if they haven't assigned reviewers or if the reviewers seem to be sitting on the work for too long.

I just use the online system to email the editor and say that I'm just looking for an update as I'm keen to see whether the paper is acceptable for publication in their journal. It hasn't affected publication outcome so far!

This is good to know. I sent mine off a good few months ago and haven't heard a squeak so will give them a chase as well.