Your baby now weighs a little over a pound is about 11 inches long. They fully fill the uterus now, but there is still plenty of room for growth. Over the next three months your baby will have the biggest weight gain.
Brain waves are beginning to activate the auditory and visual systems, causing the baby’s mouth and lips to become sensitive. Eyes will respond to light and the ears are reactive to sounds from outside of the uterus. Your baby may be able to tell when they are upside down now because their inner ear is completely developed. The brain is very active now and is regulating all other body functions.
Toenails and fingernails are growing now and may need trimmed when they are born. Blood vessels in the lungs are developing and will exchange oxygen after birth. The alveoli (the very tiny final branches of the respiratory tree) and air sacs have developed completely.
You may start to get stretch marks now. This is a normal part of pregnancy. Your health practitioner may order a blood test now to check for anemia and infection. You may also have a glucose screen between now and week twenty-eight to help rule out gestational diabetes.