7 Interesting Facts About Fetal Development in the 3rd Trimester

Full term pregnancy is considered 40 weeks counted from the first day of a your last period. Learn about the changes the developing fetus goes through during the third and final trimester.

The fetus really fills out over these next few weeks, storing fat on the body, reaching about 15-17 inches long and weighing about 4-4 ½ lbs by the 32nd week. 

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. 

Your baby's hearing is fully developed and he or she changes position frequently and responds to stimuli, including sound, pain, and light.

Here are a few of the highlights happening in your third trimester of pregnancy:

- Eyes can detect light.

- Nails begin to grow.

- Red blood cells develop in the bone marrow.

- Baby develops a firm grip.

- Limbs become chubby.

- Central nervous system matures to a stage that can control body temperature.

- Baby practices breathing.