How To Understand Fetal Development in the Third Trimester

The third trimester of the 28-40 week period is the final and most critical stage in pregnancy. This 12-week period sees a lot of changes, both on the outside (how the mother-to-be is doing) and on the inside (fetal development). This period also marks the beginning of the end… the end of the pregnancy that is! As a pregnant woman, you will be feeling very glad that you’re finally seeing the light at the end of a long tunnel. However, this is also the time when you should be most alert to any sudden changes taking place in the womb, and it is for this reason that the frequency of your visits to the gynecologist increases.

Worried about how your baby is doing in the home stretch? Here’s a breakdown of fetal development in the last trimester of pregnancy…

Week 28 – Week 31

• The baby gains weight, and by the 31st week can weigh as much as three pounds and would have grown to a length of at least 10.5 inches.
• Eyelashes are formed by the 28th week and the eyes are fully open by week 30.
• Bones have been fully formed, but will still be soft and malleable by the 29th week. The fetus begins to absorb vital minerals from the mother’s body – calcium, iron and phosphorus.
• By the 31st week, the fetus would have developed distinctive sexual characteristics. For a boy, testicles move through the groin and for a girl, the clitoris is more prominently developed.

Week 32 – Week 35

• The fetus can weigh more than 4.5 pounds, and the length will have reached about 1 foot.
• Hair covering the skin begins to fall off by week 32, and the skin coating thickens by the 35th week.
• Toenails and fingernails are developed and become visible by the 32nd and 34th weeks respectively.
• Pupils begin to react to light and can expand and contract by the 33rd week.

Week 36 – Week 40

• The fetus begins to gain weight at a faster rate than before, and by week 40 can weigh around 7.5 pounds. The baby’s length can be around 14 inches or more.
• At 37 weeks, the baby reaches full-term – most of the body organs are developed and will continue to grow.
• Antibodies are fed into the baby’s body via the placenta, and the chest expands further and grows by the 39th week.
• At this stage, sexual development also continues and by week 40, the baby is ready to be born. Around this time, the baby’s position will also change with the head facing down, ready for the birthing process.

Now that you have a full-blown idea of fetal development in the third trimester, you can lay your fears to rest and look forward to holding your baby in your arms soon!