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Third Trimester (Weeks 28 - 40) Week 39 of 40
Last reviewed by medical team: June 2026 Evidence-Based Care Check
Fetal Size Comparison

Week 39 Size: Watermelon

About the size of a sweet watermelon.

Length 50.7 cm 20.0 inches
Weight 3300 g 116.4 oz

Relative Visual Scale

Solid circle represents your baby's size. Dotted circle shows the full-term week 40 size threshold.

Inside The Womb

Baby's Development

The baby is 'full term.' The placenta continues to provide nutrients and antibodies, but it is reaching the end of its lifespan. The baby has a layer of fat and is ready for the outside world.

Weekly Milestones

  • Water Breaking Possibility
  • Placenta Antibody Transfer Complete
Maternal Health

Your Body & Symptoms

Your cervix is ripening (softening, dilating, and thinning). Your water might break, either as a gush or a slow trickle. If this happens, contact your provider.

Common Symptoms this Week

Water breaking possibility Frequent, intense Braxton Hicks Diarrhea (body clearing out for labor) Lower backaches

Doctor & Care Recommendations

  • If your water breaks, note the time, color, and odor, and call your doctor.
  • Double-check that you have all necessary items for postpartum recovery.
  • Keep walking gently to help encourage labor.

Weekly Health Guides & Resources

Trimester Guide

Third Trimester Guide

Read comprehensive clinical milestones, screening checklists, and developmental guidelines for this phase.

Explore Trimester →
Common Symptoms

Track & Relieve Symptoms

Learn why symptoms occur, home remedies, and clinical indicators for this week:

Pregnancy Nutrition

Food Safety Checklists

Verify safety statuses, listeria and mercury risks, and safe alternatives for:

Full Nutrition Guide →

Frequently Asked Questions: Week 39

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