Sucking in

I've always had an issue with my weight, most of which goes straight to my belly, so much so that even before being pregnant I've had people ask how far along I am, super rude. Anyways, I've always sucked my tummy in, to the point where I do it without even thinking about it. Now being 20week pregnant with my first, I don't really have a need, I want to embrace my bump, but I keep finding myself sucking in and have to remind myself not to. Could this hurt or effect baby at all? Anyone else have a similar problem??