At week 23 the baby is a little over 8 inches long and about 1 ¼ pounds. The baby is starting to make some fat under the skin. This will change the way the baby appears on the ultrasound. Up until now the ultrasound pictures look like a little skeleton. They almost have an alien appearance. As the baby starts to make fat tissue the appearance will begin to change. The baby starts to look more human. The facial features are filling out and the skin is less translucent ant saggy.
Week 23 is a bit of a milestone. This is the first gestational age in which the baby has a chance of survival outside of the womb. Babies born at 23 weeks have about a 1/3 survival rate. Of the babies that survive, about 60% will have some significant disability. As you can see, these odds are not great and you certainly do not want to have a baby at 23 weeks. If the baby is born at 23 weeks there is some chance of it doing OK. Of note, we consider 24 weeks to be the “age of viability” because 24 weeks is the first gestational age where the chance of survival is greater than 50%. Healthcare continues to advance and these numbers continue to improve. It is possible the age of viability will be at an earlier gestational age as technology continues to improve.