Fetal Development During the Third Trimester

Weekly developments

Week 28

Baby’s eyes are open and are sensitive to light; eyelashes have formed. The wrinkles on the skin begin to smooth out due to the fat deposited in the skin.

Week 29

During this period, the baby’s bones are fully developed but not yet strong. The touch receptors are now fully developed.

Week 30

The baby’s eyes are now wide open most of the time. Red blood cells begin to form in the bone marrow. And, the baby’s head might have enough hair.

Week 31

The baby’s head is more in proportion to the body and the central nervous system can now regulate temperature. The vernix and lanugo, which covered and protected the baby for weeks, begin to disappear.

Week 32

The baby starts to practice breathing on its own and can turn the head from side to side. The toenails are now visible. The baby begins to absorb minerals. The skin becomes opaque. The baby sleeps most of the day. A decrease in the baby’s movement might be felt because the uterus is now small for the baby.

Week 33

The baby can now detect light and the pupils can either dilate or constrict. Some baby movements are seen on the mother’s abdomen.

Week 34

The baby’s skin is pinkish and the fingernails have reached the fingertips.

Week 35

The baby is gaining weight quickly. Consequently, the limbs become chubby.

Week 36

The skin is red and smooth.

Week 37

During this stage, the baby is considered early-term. The organs are ready to work on their own. Fat deposits continue to form. And in preparation for birth, the baby’s head starts to descend into the pelvis.

Week 38

A firm grasp is developed during this time. The baby has shed all of the lanugo. The baby might weigh about 6.5 pounds.

Week 39

The baby’s fingernails have grown beyond the fingertips. Fine hair remains on the arms and shoulders. The placenta continues to supply antibodies that will help fight infection after birth. The chest has become more prominent.

Week 40

The baby is now fully developed or is full term. The baby may weigh seven to eight pounds and could be 18 to 20 inches long.

During the final weeks of pregnancy, the baby’s first poop starts to build up in the baby’s intestines. The poop consists of vernix, lanugo, and blood cells (mostly).

There’s no need to worry if your due date comes and goes and you’re still not giving birth yet. It’s normal to have the baby a week or two early or late from your due date.