Your baby is basically finished growing now -- he's just hanging out and packing on the ounces (about eight of them a week!), building up those cute fat layers. He weighs about 5.5 to 6 pounds and stretches out crown to toes at 17 to 18 inches. There's not too much room in there for moving around, so even the slightest movement or repositioning can be very uncomfortable for you. You might even see the outlines of tiny elbows and feet bulging out from your belly.
Even if your baby's actions aren't so dramatic anymore, you should still keep tabs on his general activity levels. Keep doing kick counts if you can, but just try to be aware of his movement trends and contact your doctor or midwife if there seems to be a significant decrease.
Your baby's kidneys are functioning now, and his liver is processing waste. His skull is formed but hasn't fused yet so he can squeeze through the birth canal. His lungs are producing surfactant, which helps the lungs expand and keeps them from collapsing. He'd probably be perfectly healthy if he were born today but would spend a few extra days in the hospital before going home.