Third Trimester
Week 39: Full term! The vast majority of organs are now fully mature.
Here's everything happening with your baby and your body this week.
Your baby is the size of a
Watermelon
Length
20 in
Weight
3.3 kg
Week
39 / 40
💡 Expert tip
If your water breaks, call your provider immediately even if you have no contractions. If contractions are 5 minutes apart, lasting 60 seconds, for 1 hour — go to the hospital.
🌱 Baby's development this week
- Fully mature in virtually all organ systems
- Continues gaining weight and developing brain
- Skull bones not fully fused — allows passage through birth canal
- Ready for the world
Science fact
During vaginal birth, babies are exposed to the mother
🤰 Your symptoms this week
Regular mild contractions
Braxton Hicks or early labor; track them for regularity
Practice contractions — normal from mid-pregnancy. Stay hydrated, change position, rest.
Lower back pain intensifying
a sign the baby is pressing on the sacrum
Prenatal yoga, a support pillow, and swimming all help. Avoid standing for long periods.
Nausea
a common sign that labor is near; your body clearing the digestive tract
Try ginger tea, crackers before getting up, or vitamin B6 (10mg 3x/day). Small meals every 2 hours help.
💛 Changes in your body
- Dilation and effacement ongoing
- May feel the baby
- further into pelvis
- Contractions becoming more regular
- Extreme readiness and impatience are normal
💙 Mental health this week
Every day you feel
🥗 Nutrition focus
- Dates (6/day) have been associated with less need for oxytocin augmentation during labor in multiple studies
- Light meals only — active labor is easier on an empty or lightly filled stomach
- Stay hydrated — contractions, especially false labor, are worsened by dehydration
📅 Appointment / test
39-week appointment: discuss induction preferences and timing with your provider. Most offer elective induction at 39 weeks.
✅ This week's checklist
Apply the 5-1-1 rule for hospital: contractions every 5 min, lasting 1 min, for 1 hour
Rest between contractions if in early labor at home
Call your provider immediately if water breaks, you have heavy bleeding, or baby stops moving
Track your pregnancy week by week
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