I didn't mean to alarm you by my response. Actually, decreased movement is very common the further along you are in pregnancy, as the baby runs out of room to move around. This is not the case for every pregnancy though, some babies are active from 18wks to delivery, my 1st pregnancy with my son was. However, fetal stress tests should have been performed on you by or before 40wks.
You are 40 wks pregnant and not in the hospital delivering yet? I know some pregnancies can continue to 42 wks, but at this point you should be watched and monitored very closely by your OB. When is your due date? What does your OB say? Decreased fetal movement can be a sign of fetal distress, it is very important you contact your OB sooner than later! Good luck!