at 12 weeks babys not really big enough to be sitting on anything...<br><br>
however right around 12 weeks is when your uterus starts to come up out of your pelvis, so perhaps you feel it getting tighter down there?
Water! Lots of water!<br><br>
Actually, the other day when I was at WF, I ended up feeling crampy, too. I tried to rest more and drink a bunch, and it eventually went away. It is getting SO hot here that I think it's easy for us to get dehydrated without realizing it. Also, make sure to get electrolytes. I was drinking a ton but it was passing through VERY quickly (like I couldn't watch a 30min DVR'd show - so more like 20min - without needing to go). I realized I was probably low on electrolytes, and some coconut water seemed to help.
Its normal to feel crampy while your uterus is stretching . Round ligaments are the ligaments surrounding your uterus and can cause pain with sudden movement and/or over doing it.<br><br><a href="http://www.babycenter.com/0_round-ligament-pain_205.bc" target="_blank">http://www.babycenter.com/0_round-ligament-pain_205.bc</a>