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Trimester 3

38 Weeks Pregnant

In week 38, your baby is putting on weight quickly and fine-tuning their lung and brain function. They are becoming more responsive to light and sound from the outside world as they prepare for the big transition to life outside.

8 min read Medically Reviewed Updated 2024-05-01
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Your baby is the size of a Leek
50 cm
Length
3.1 kg
Weight
Week 1Week 13 - End of Trimester 1Week 27Week 42

Baby's Development This Week

In week 38, your baby is putting on weight quickly and fine-tuning their lung and brain function. They are becoming more responsive to light and sound from the outside world as they prepare for the big transition to life outside.

  • The fetus sheds the remaining vernix and lanugo into the amniotic fluid.
  • The baby swallows the amniotic fluid, contributing to meconium (first stool).
  • Firm grasp reflex is established.
  • All organ systems are mature and functional.
  • The baby's head circumference is nearly equal to the abdomen.
  • About 49.8cm — the size of a leek.

Your Symptoms at Week 38

As you progress through week 38, you may feel more physical strain as your baby grows. Back pain and difficulty finding a comfortable sleeping position are common. Keep your feet up when you can and take pride in how far you've come in this incredible process.

Pelvic pressure and pain
Birthing ball, warm baths, and rest. (severe)
Braxton Hicks (frequent)
Practice breathing; they may be harder to distinguish from real labor. (moderate)
Insomnia
Rest when you can; your body is preparing. (severe)
Swelling
Elevate feet; drink plenty of water. (moderate)
Anxiety and excitement
Focus on relaxation techniques; talk about your feelings. (moderate)

When to Call Your Doctor

  • Contractions following the 5-1-1 pattern
  • Water breaking (even a slow trickle)
  • Decreased fetal movement
  • Heavy bleeding
  • Feeling of intense pressure like you need to push

Week 38 Checklist

  • Attend weekly prenatal visit (essential)
  • Review your hospital route and backup plan (essential)
  • Finalize who will be in the delivery room (recommended)
  • Have newborn essentials ready at home (essential)
  • Consider perineal massage to reduce tearing risk (optional)

Nutrition in the Third Trimester

By the third trimester, your baby’s growth is at its fastest, and it’s common for appetite, digestion, and comfortable meal sizes to shift again as the growing uterus puts more pressure on the stomach. Many people find smaller, more frequent meals more comfortable than large ones during this stage, and heartburn becomes more common as a result of this physical pressure.

  • Continue your prenatal vitamin through the end of pregnancy — some providers also recommend starting or adjusting iron supplementation in the third trimester depending on bloodwork.
  • Smaller, more frequent meals can ease the heartburn and fullness that often become more pronounced as the uterus takes up more abdominal space.
  • Stay well hydrated — fluid needs remain elevated, and dehydration can contribute to Braxton Hicks contractions.
  • Continue prioritizing protein, iron, and calcium, which remain important for your baby’s rapid growth in the final weeks.
  • Some people find preparing and freezing meals ahead of delivery useful, since appetite and energy for cooking can fluctuate in these final weeks.
  • Continue avoiding alcohol, raw/undercooked proteins, unpasteurized dairy, and high-mercury fish through the end of pregnancy.

Staying Active in the Third Trimester

Exercise in the third trimester often needs to be scaled back in intensity as the belly grows larger and balance becomes more of a factor, but staying appropriately active (if cleared by your provider) can still help with sleep, mood, and physical comfort in these final weeks. Walking and prenatal-specific stretching or yoga are commonly well-tolerated options. Pay attention to your body’s signals more than usual here — this is a stage where providers generally recommend erring toward caution and lower intensity rather than pushing to maintain a pre-pregnancy pace.

For Partners: Supporting the Third Trimester

The final stretch of pregnancy often brings physical discomfort, disrupted sleep, and anticipation (or anxiety) about labor — partners can help by taking on more of the physical tasks around the house, being flexible and present as due-date logistics come together, and learning what to expect during labor so they can be a more active, informed support during delivery. This is also a good time to finalize practical plans together: the route to the hospital or birth center, who to call, and what the first hours after birth might look like.

Frequently Asked Questions

Medical Disclaimer: This content is for informational purposes only and is not a substitute for professional medical advice. Always consult your healthcare provider for personalized guidance about your pregnancy.