18 weeks Dec. 15, 2009 • Size: Length 5-5.5 in, weight 5-7oz, Size Soda Can
Week 18 -
" Not only can your baby tune in the world around it now, it's also equipped to react to it. When startled by a loud noise, say, it might reflexively curl up into a little ball."
-Ages and Stages
"Head to rump, your baby is about 5 1/2 inches long (about the length of a bell pepper) and it weighs almost 7 ounces. It's busy flexing the arms and legs — movements that you'll start noticing more and more in the weeks ahead. The blood vessels are visible through the thin skin, and the ears are now in their final position, although they're still standing out from the head a bit. A protective covering of myelin is beginning to form around the nerves, a process that will continue for a year after it's born. If you're having a girl, her uterus and fallopian tubes are formed and in place. If you're having a boy, his genitals are noticeable now, but he may hide them from you during an ultrasound." - Baby Center
Week 17 -
" Your baby's skeleton is changing from soft cartilage to bone, and the umbilical cord — her lifeline to the placenta — is growing stronger and thicker. Your baby weighs 5 ounces now (about as much as a turnip), and she's around 5 inches long from head to bottom. She can move her joints, and her sweat glands are starting to develop."
- Baby Center