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Fetal Development in the Third Trimester

Fetal Development in the Third Trimester - When Does Life Begin?

Fetal Development in the Third Trimester - When Does Life Begin?By the third trimester, your baby is already so developed — but still requires a little more time and nourishment for all its organs to be fully functional. Here’s a weekly breakdown of fetal development in the third trimester:

Week 27 (25 weeks following conception): The third trimester starts off strong, as the fetus can now open and blink its eyes. Eyelashes grow and frame its newly pigmented eyes!

Week 28 (26 weeks following conception): The fetus is now preparing for its grand arrival, as it begins turning head-down. The fetus may be startled by loud noises and even cry within the womb. At this point, the fetus weighs 2-3 pounds. 

Week 29 (27 weeks following conception): As the fetus continues growing and developing, you may feel more movement within the womb. It’s a tight squeeze and they’re still kicking and grasping.

Week 30 (28 weeks following conception): The fetus may have a good amount of hair on its head at this point. Its brain is quickly developing and it can now control its own body temperature.

Week 31 (29 weeks following conception): It’s the final countdown! With only 9 weeks to go, the fetus will begin putting on weight rapidly. Most of the major components of development are complete. However, the fetus will continue to process more information and stimuli. The fetus is becoming more aware and learning. You may notice more distinct patterns in when the fetus is awake and when it’s asleep.

Week 32 (30 weeks following conception): The fetus’s skin is no longer transparent and the hair coating it (lanugo) begins falling out.

Week 33 (31 weeks following conception): The fetus’ bones are hardening, except for the skull; the fetus’ head must remain soft and pliable to pass through the birth canal. The fetus’ pupils may dilate in response to light.

Week 34 (32 weeks following conception): The vernix coating the fetus’ skin begins to thicken and the fetus’ nails now reach its fingertips. 

Week 35 (33 weeks following conception): At this stage of development, the fetus’ brain is growing quickly, weighing ⅔ of what it will at birth. With rapid weight gain, the fetus’ limbs are now chubby. 

Week 36 (34 weeks following conception): The fetus weighs 6-7 pounds.

Week 37 (35 weeks following conception): Now head-down, the fetus may begin to descend into your pelvis as it prepares for delivery.

Week 38 (36 weeks following conception): The fetus has “filled out” so much that it’s head has about the same circumference as its abdomen. It is putting on about ½ pound weekly.

Week 39 (37 weeks following conception): You are now considered full-term! In the last week of pregnancy, the fetus continues putting on fat to keep it warm outside the womb. At this time, the chest becomes more prominent.

Week 40 (38 weeks following conception): You have reached your due date, meaning your baby should arrive any day now. Just remember — due dates are estimates! Be patient as your baby prepares to enter the world soon.

 

Learn more about the various stages of fetal development (conception, first, second, and third trimester) and don’t forget to follow us on social media (Facebook, Instagram, and TikTok).

 

Sources:

Mayo Clinic

Cleveland Clinic

Jackson Health System

NBC News