The Final Countdown: What Happens During the Third Trimester of Pregnancy
At Open Arms Real Choices Clinic, we believe that empowered education leads to confident, informed decisions. That’s why we’ve created this series on The Stages of Pregnancy—to walk with you through each trimester with clarity and care. As we arrive at the final stretch, let’s explore the incredible milestones of third-trimester fetal development.
What to Expect in the Third Trimester
The third trimester of pregnancy fetal development typically spans weeks 29 through 40. During this time, your baby’s growth and weight increase significantly, and essential organ systems, particularly the brain and lungs, approach full maturity. You may often hear that pregnancy lasts nine months, but a full-term pregnancy actually reaches 40 weeks—closer to ten months. As your due date approaches, your provider will carefully monitor both you and your baby. If labor doesn’t begin naturally after 40 weeks, induction may be considered to help start the process.
Month 8: Weeks 29–32
At this stage, your baby becomes more active and responsive. Third-trimester fetal brain development accelerates, laying the groundwork for life outside the womb. Though most internal systems are well developed, the lungs may still need more time.
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Baby can see and hear clearly
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Bones are soft but fully formed
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The body begins storing key minerals like calcium and iron
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Lanugo (the soft hair from the second trimester) begins to shed
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Size: Approximately 15–17 inches long and 4–4.5 lbs, gaining about half a pound each week
Month 9: Weeks 33–36
Your baby’s growth and reflexes continue to develop rapidly. Movements may become more coordinated, and their personality may even begin to shine through with recognizable patterns.
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Lungs are nearly mature
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Reflexes such as blinking, grasping, and head-turning are developed
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The vernix (a protective skin coating) becomes thicker
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Baby may respond to touch, sound, and light
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Size: Approximately 16–19 inches long and 6–6.5 lbs
Month 10: Weeks 37–40
This is it—your baby is considered full-term and could arrive at any time! As space becomes tight in the womb, movements may slow down, but your baby is likely shifting into a head-down position in preparation for birth.
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Organs are fully developed and can function independently
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You may feel pressure as baby “drops” into your pelvis
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Size: Typically 19–21 inches long and 6 lbs 2 oz to 9 lbs 2 oz
A Time of Anticipation and Joy
The final weeks of pregnancy bring anticipation, excitement, and sometimes a bit of discomfort. But this season of waiting is filled with purpose—each day brings your baby closer to being ready for the outside world.
Need Support During Your Pregnancy?
Whether you’re preparing for your first child or simply looking for support during your pregnancy journey, Open Arms Real Choices Clinic is here for you. We offer free pregnancy testing, limited obstetric ultrasounds, and compassionate care in a confidential setting. You’re not alone—we’re here to walk with you every step of the way.
Contact us today to schedule your appointment and let us help you take your next step with confidence.
