Not stupid! Fundus is the top of your uterus. Most OBs/MWs will measure it from your pubic bone every appt and you should roughly measure one cm for every week along you are. Towards the end of DS pregnancy mine was way off and none of the OBs I saw (5 of them in that practice) even cared so I am not sure how telling it is.
Meg, Momma to Joey (Feb 2010)