My baby is the size of a medicine ball this week, she is between 19-19.5 inches and 4.5 pounds. She gains about 1/2 and ounce a day. Her lungs are approaching maturity, the lungs are the last organ to fully develop.
She moves a lot but a lot less kicking because she is so cramped. She does more twisting and wiggling like a new born would. It is so fun to feel her moving around, I can't wait till I can play with her.