from Babycenter

How your baby's growing: Your baby now weighs about 4 3/4 pounds and is probably almost 18 inches long. Her fat layers — which she'll need to regulate her body temperature once she's born — are filling her out, making her rounder. Her central nervous system is still maturing and her lungs are well developed by now. If you've been nervous about going into preterm labor, you'll be happy to know that 99 percent of babies this age can survive outside the womb — and most have no major long-term problems related to prematurity.