35/35 and menstrual cramps

Davesgrl2011

I am 35 weeks today (yay!) but yesterday evening into this morning I've been what can only be described as menstrual cramps- very low down in my abd just like when I was getting my period.  In fact, a few times I actually forgot I was pregnant and went into the bathroom fully expecting to see that my period had started.  It isn't intense, and there is no pattern, but it definately comes and goes, sometime with the hard BH tummy.  I am sure it is not labor (right?!?!?) but could anyone explain what the heck it is?  I have my OB app tomorrow morning.

Thanks!