This week, your baby weighs about 3 pounds and measures around 17 inches from head to toe. She'll gain half a pound or so every week for the next seven weeks.
Your baby can control her body temperature now, which means that she'll start losing her lanugo, the fine, downy hair that's been keeping her warm for the past few months. Her proportions are also becoming more like a newborn's; her head is no longer huge in comparison to the rest of her body, and her legs are lengthening quickly. Her eyebrows, eyelashes, fingernails and toenails should be fully formed.
As far as the baby's inner workings are concerned, her nerve fibers are now encased in myelin, which allows nerve impulses to zoom around her body much more quickly and efficiently. Her brain's surface, previously smooth, is becoming wavy and ridged (and more powerful). Her bone marrow is now doing all the blood production work.
Your baby still has quite a bit of room to grow in there, even though it might seem to you that the opposite is true. Hard to believe that she could gain 4 to 6 more pounds, isn't it?