Sorry to disagree here, but I've been told it's a bad idea to use antibacterial anything on a piercing. It kills something necessary to make it heal (if only I could remember what exactly!), making the body continue to try to reject the bar rather than heal around it. Salt water is all that's needed, because it cleans without killing [whatever it's called ]

It's strange that an already-healed piercing has suddenly become infected (or is on the way to infection), so I'd say it probably is the fact you're pregnant. If your belly has started to pop out, it might have caused a small cut/break in the skin, which has become infected...