Third trimester

Weeks 27 Thru 32 – Gestational Age (Fetal Age – Weeks 25 Thru 30):

The lungs are not fully mature yet, but some rhythmic breathing movements are occurring. The bones are fully developed, but are still soft and pliable. The fetus is storing its own calcium, iron and phosphorus. The eyelids open after being closed, since the end of the first trimester.
Weeks 33 Thru 36 – Gestational Age (Fetal Age – Weeks 31 Thru 34):

This is about the time that the fetus will descend into the head down position preparing for birth. The fetus is beginning to gain weight more rapidly. The lanugo hair will disappear from the skin, and it is becoming less red and wrinkled

Weeks 37 Thru 40 – Gestational Age (Fetal Age – Weeks 35 Thru 38):
The fingernails have grown long and will need to be cut soon after birth. Small breast buds are present on both sexes. The mother is supplying the fetus with antibodies that will help protect against disease. All organs are developed, with the lungs maturing all the way until the day of delivery.