Pregnancy Third Trimester: Your Baby?s Development

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During your third trimester, your child will open his or her eyes for the first time and get ready for life outside the womb.

Pregnancy Third Trimester: Week 28 – Baby Opens Eyes
Now that you’re 28 weeks into your third trimester, your baby’s eyelids are starting to open and their eyelashes are completely formed. They are starting to gain weight rapidly and the wrinkles in the skin are smoothing out. Your baby should now be nearly 10 inches long and weight almost 2-1/4 pounds. Healthy babies born in the 28th week have a 90% chance of surviving without any neurological or physical impairments, although these odds continue to get better with each week spent in the womb.

Pregnancy Third Trimester: Week 29 – Bones are Developed Completely
In your 29th week of pregnancy, your baby’s bones remain soft but are now fully formed and developed.

Pregnancy Third Trimester: Week 30 – Baby’s Eyes Open Wide
Your baby now spends most of his or her time with wide open eyes. They probably have a full head of hair and red blood cells are forming in the bone marrow. Your baby measures over 10-1/2 inches and weighs close to three pounds.

Pregnancy Third Trimester: Week 31 – Continued Sexual Development Occurs
Now that you’re 31 weeks into your pregnancy, the central nervous system (CNS) is completely developed and now controls your baby’s body temperature on its own.

Pregnancy Third Trimester: Week 32 – Breathing Practice Begins
Your baby now has visible toenails. Despite lungs that aren’t yet fully formed, your baby is practicing breathing in preparation for birth. Your child’s body is starting to absorb minerals like calcium from their intestinal tract while the lanugo covering is falling off. Your baby is around 11 inches long and weighs almost 3-3/4 pounds.

Pregnancy Third Trimester: Week 33 – Light Detection
Your baby begins to detect light during the 33nd week of pregnancy as the pupils can now dilate and constrict.

Pregnancy Third Trimester: Week 34 – Fingernails are Growing
By the 34th week of pregnancy, your child’s fingernails should now reach the tips of their fingers. While the lanugo has now fallen off, the vernix caseosa, or white coating on the baby’s skin, continues to thicken. Your baby measures 12 inches long.

Pregnancy Third Trimester: Week 35 – Vernix Caseosa Thickens
Your child’s arms and legs are now getting thicker with fat and the vernix caseosa continues to thicken. From the 35th week on, your baby will gain around half a pound per week for a solid month.

Pregnancy Third Trimester: Week 36 – Quick Weight Gain Occurs
Your baby may now have a harder time moving inside your womb as they are quickly gaining weight. You’ll probably still feel rolls and stretches from your child but it’s important to perform kick counts during this stage to make sure your baby is moving enough.

Pregnancy Third Trimester: Week 37 – Full Term
At 37 weeks into your trimester, your child is officially full term. All of your baby’s organs can now function on their own and your baby may now descend into a head-down position to prepare for birth.

Pregnancy Third Trimester: Week 38 – Baby Has Firm Grasp
Your baby is now developing a firm grasp 38 weeks into your pregnancy. Your child’s toenails are at the tips of his or her toes while their brain weighs around 14 ounces. Your baby’s brain continues to grow after birth, though. Nearly all of the lanugo is shed. Your baby weighs around 6-1/2 pounds now.

Pregnancy Third Trimester: Week 39 – Placenta Supplies Antibodies
At 39 weeks, your baby’s chest is becoming prominent while the testes are still descending into the scrotum if you’re having a boy. The placenta will keep supplying your baby with important antibodies to fight possible infections after birth, although breastmilk can provide additional protection.

Pregnancy Third Trimester: Week 40 – Due Date is Near
Your baby is now around 18 to 20 inches long and weighs anywhere from 6 pounds to 9 pounds. Your baby may arrive by your due date, although it’s common for babies to come up to 2 weeks late or early.