Jacob is 6 months old!

Bring on the bulk! Baby gains about 6 ounces this week. The weight is in muscle, bone mass and organs.

His body begins to fill out with his appearance increasingly becoming more like a newborn.

Taste buds begin to form. If mom drinks something strange or bitter, baby may be observed showing his distaste.

Little creases have appeared on his palms. The muscular coordination of his hands has improved as he sucks his thumb.

Over the next seven days the sweat glands will be forming in the skin.

His lungs are developing "branches" of the respiratory "tree" and cells that produce surfactant, a substance that helps the air sacs inflate easily.

This week your baby is officially considered viable. (Finally!)

Baby weighs 1.3 pound and is 11.8 inches long -- almost the length of a ruler!