Hard belly

Lidia

So I have noticed that sometimes my belly becomes rock hard. It is not the baby’s body parts sticking out because it is hard all over my belly no matter where I touch it...than this goes away within a couple minutes maybe and belly feels normal as usually. I have no pain whatsoever associated with it, just that the belly feels very very hard to touch. Does anyone know what it may be? I will talk about it with my OB in February.