As you get further along the baby can run out of room so he/she may not move as much anymore. Here is some more in depth info :
Once you're in your third trimester, some practitioners will recommend that you spend some time each day counting your baby's kicks. There are lots of different ways to do these "kick counts," so ask for specific instructions.
Here's one common approach: Choose a time of day when your baby tends to be active. (Ideally, you'll want to do the counts at roughly the same time each day.) Sit quietly or lie on your side so you won't get distracted. Time how long it takes for you to feel ten distinct movements – kicks, punches, and whole body movements all count. If you don't feel ten movements in two hours, stop counting and call your midwife or doctor.
at 7:54 PM on Jan. 25, 2011