31 Weeks Pregnant: Almost There

At 31 weeks pregnant, your baby is about the size of a coconut, measuring around 16.2 inches (41 cm) from head to heel and weighing approximately 3.3 pounds (1.5 kg). Your baby has finished most major developmental milestones, and from here forward, the focus is on growth and organ maturation in preparation for life outside the womb.¹

What’s Happening at 31 Weeks Pregnant?

You’re now just 9 weeks (about 2 months) from your due date! Week 31 marks an exciting transition where your baby’s major development is complete. All organs and body systems are formed and functional, though they’ll continue maturing over the remaining weeks.²

At this stage, you’re likely feeling very pregnant. Your belly is large, movement can be uncomfortable, and you may be experiencing a range of third-trimester symptoms. At the same time, anticipation is building as you get closer to meeting your baby.

Your uterus now extends about 4.5 inches (11 cm) above your belly button, and your total weight gain is likely around 21-27 pounds if you started at a healthy weight.³

How Big is My Baby at 31 Weeks?

Your baby at 31 weeks is about the size of a coconut, measuring approximately 16.2 inches (41 cm) from crown to heel.⁴

Weight-wise, your baby now weighs around 3.3 pounds (1.5 kilograms). From this point forward, your baby will gain about half a pound per week as they build the fat stores essential for maintaining body temperature after birth.

Baby Development at Week 31

While major organ development is complete, important maturation continues:

Brain connections: Your baby’s brain is rapidly forming trillions of neural connections (synapses). The brain will continue this rapid development through early childhood, but the foundation is being built now.⁵

Fat accumulation: Your baby is adding significant amounts of fat, which smooths out skin, provides energy reserves, and helps regulate body temperature. This is why babies born closer to term tend to have chubbier, healthier appearances.

Lung maturation: Your baby’s lungs are producing more surfactant each day. While lungs aren’t fully mature until closer to 37 weeks, babies born at 31 weeks have excellent survival rates (over 95%) with neonatal care, though they often need respiratory support.⁶

Five senses functional: All five senses are working. Your baby can see light and shadows, hear sounds inside and outside the womb, taste flavors in amniotic fluid, respond to touch, and smell (though there’s nothing to smell in the amniotic sac).

Rapid eye movements: Your baby’s eyes can move in all directions now, and they open and close regularly.

Fingernails and toenails: These are fully formed and may even need trimming soon after birth.

Digestive system practice: Your baby’s digestive system is functional and ready for milk, though the intestines are still maturing.

Regular sleep-wake cycles: Your baby has established patterns of sleep and wakefulness, though these may not align with your schedule!

Movement changes: As space becomes tighter, you may notice fewer big movements and more stretches, rolls, and pokes. The quality of movement changes, but frequency should remain consistent.⁷

Common Symptoms at 31 Weeks Pregnant

Physical discomfort often peaks in late pregnancy:

Shortness of breath: Your uterus pushes high against your diaphragm, making deep breaths difficult. This often improves in the final weeks when your baby drops lower (lightening).⁸

Frequent urination: Your baby is pressing on your bladder constantly. You may feel like you need to urinate even when your bladder is nearly empty.

Heartburn and indigestion: These symptoms often worsen in late pregnancy as your stomach is compressed upward.⁹

Braxton Hicks contractions: Practice contractions may become more frequent and sometimes uncomfortable. Unlike true labor, these remain irregular and don’t increase in intensity.

Pelvic pressure and pain: As your baby settles lower in your pelvis, you may feel increased pressure and discomfort in your pelvic area. Some people experience symphysis pubis dysfunction (SPD), painful separation of the pelvic joint.

Back pain: Carrying significant weight in your abdomen strains your back muscles, and the hormone relaxin loosens ligaments, contributing to pain.¹⁰

Swelling: Mild swelling in feet, ankles, and hands is normal. Severe or sudden swelling, especially with headache or vision changes, requires immediate medical attention.

Trouble sleeping: Physical discomfort, frequent urination, heartburn, and anxiety about labor make sleep challenging.

Fatigue: The physical demands of late pregnancy can be exhausting.

Rib pain: Your baby may push or kick against your ribs, causing discomfort.

Leaking colostrum: Your breasts may leak small amounts of colostrum, the nutrient-rich first milk your baby will receive.

When to Call Your Doctor

Contact your healthcare provider immediately if you experience:

• Regular, rhythmic contractions (4+ per hour)
• Fluid leaking or gushing from your vagina
• Vaginal bleeding
• Severe headache with vision changes
• Sudden severe swelling
• Significant decrease in fetal movement
• Severe abdominal pain
• Upper right abdominal pain with nausea (possible liver issue)

Tips for Week 31

Monitor fetal movement: Continue tracking your baby’s kicks and movements. While the quality may change (more pushing, less rolling), the frequency should remain consistent. If you notice decreased movement, contact your provider.¹¹

Prepare for Group B strep testing: Around weeks 35-37, you’ll be tested for Group B streptococcus (GBS), a common bacteria that can affect newborns. Testing involves a vaginal and rectal swab.

Finalize your birth plan: Discuss your preferences with your healthcare provider and make sure your support person understands your wishes. Remember that birth plans are flexible guides, not contracts.

Practice labor positions: Try different positions—squatting, hands and knees, sitting on a birth ball, side-lying—to see what feels comfortable and to build confidence for labor.

Pack your hospital bag: Have it ready by week 36 at the latest. Include comfortable clothes, toiletries, phone charger, snacks, nursing bra if planning to breastfeed, and baby’s going-home outfit.

Install car seat: Don’t wait until the last minute. Install your car seat now and have it inspected by a certified technician. You can’t leave the hospital without one properly installed.

Rest when possible: Listen to your body. If you’re tired, rest. The final weeks of pregnancy are demanding, and you’ll need energy for labor and caring for a newborn.

Stay active safely: Continue gentle exercise like walking or swimming if you’re able, but don’t push yourself. Exercise can help with stamina for labor and may improve mood and sleep.¹²

Manage heartburn: Eat small frequent meals, avoid trigger foods, stay upright after eating, and sleep with your upper body elevated.

Prepare meals to freeze: Cook and freeze meals now while you have some energy. You’ll be grateful for easy dinners in those early postpartum weeks.

Stay hydrated: Drink plenty of water throughout the day to support blood volume, amniotic fluid, and overall health.

Preparing for Labor and Delivery

With 9 weeks to go, final preparations are important:

Know the signs of labor: Regular contractions that increase in intensity and frequency, water breaking (gush or trickle), bloody show (mucus plug with blood), and pelvic pressure.

Understand when to go to the hospital: Many providers recommend the 5-1-1 rule for contractions: 5 minutes apart, lasting 1 minute each, for 1 hour. However, always call your provider for guidance based on your specific situation.

Create a support network: Make sure your support person knows the plan, you have backup transportation to the hospital, and you have help lined up for the early postpartum period.

Learn pain management options: Understand both medical options (epidural, IV pain medication) and non-medical options (breathing, position changes, hydrotherapy, massage).

Discuss induction: If you’re at risk for going past your due date, talk with your provider about when and why they might recommend induction.

Countdown to Meeting Your Baby with Nooko

You’re in single digits now—less than 9 weeks to go! Nooko helps you prepare for labor with a contraction timer, kick counter, and countdown to your due date. Track your symptoms, log movements, and access evidence-based information about what’s happening during week 31.

Share your data with your healthcare provider and feel confident that you’re monitoring your pregnancy closely as you approach delivery.

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References

Footnotes

1. Mayo Clinic. (2024). “Fetal development: The 3rd trimester.” https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/fetal-development/art-20045997 ↩

2. American College of Obstetricians and Gynecologists. (2025). “How Your Fetus Grows During Pregnancy.” https://www.acog.org/womens-health/faqs/how-your-fetus-grows-during-pregnancy ↩

3. American College of Obstetricians and Gynecologists. (2025). “Weight Gain During Pregnancy.” https://www.acog.org/womens-health/faqs/weight-gain-during-pregnancy ↩

4. BabyCenter. (2025). “31 Weeks Pregnant.” https://www.babycenter.com/pregnancy/week-by-week/31-weeks-pregnant ↩

5. Mayo Clinic. (2025). “Fetal development: The 3rd trimester.” https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/fetal-development/art-20045997 ↩

6. Merck Manual. (2025). “Respiratory Distress Syndrome in Newborns.” https://www.merckmanuals.com/home/children-s-health-issues/lung-and-breathing-problems-in-newborns/respiratory-distress-syndrome-in-newborns ↩

7. Tommy’s. (2025). “Your baby’s movements in pregnancy.” https://www.tommys.org/ ↩

8. American College of Obstetricians and Gynecologists. (2025). “Exercise During Pregnancy.” https://www.acog.org/womens-health/faqs/exercise-during-pregnancy ↩

9. American College of Obstetricians and Gynecologists. (2025). “Problems of the Digestive System.” https://www.acog.org/womens-health/faqs/problems-of-the-digestive-system ↩

10. American College of Obstetricians and Gynecologists. (2025). “Back Pain During Pregnancy.” https://www.acog.org/womens-health/faqs/back-pain-during-pregnancy ↩

11. American College of Obstetricians and Gynecologists. (2025). “Fetal Movement Counting.” https://www.acog.org/ ↩

12. American College of Obstetricians and Gynecologists. (2020). “Physical Activity and Exercise During Pregnancy.” https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2020/04/physical-activity-and-exercise-during-pregnancy-and-the-postpartum-period ↩