25 Weeks Pregnant: Baby's Senses Are Developing Rapidly

At 25 weeks pregnant, your baby is about the size of a rutabaga, measuring around 13.6 inches (34.6 cm) from head to heel and weighing approximately 1.5 pounds (660 grams). Your baby’s lungs are developing rapidly, their senses are becoming more refined, and they’re beginning to respond to sounds and light.¹

What’s Happening at 25 Weeks Pregnant?

You’re officially in the final weeks of your second trimester, with the third trimester just around the corner. Week 25 brings continued rapid development for your baby and new physical changes for you as your uterus expands.

Your baby is becoming more active, and you’re likely feeling regular movements now—kicks, rolls, and somersaults as they explore their increasingly snug living quarters. Many people find this one of the most enjoyable parts of pregnancy, as you can clearly feel your baby’s presence and personality emerging.²

Your uterus has grown significantly and now reaches about halfway between your belly button and breastbone. This expansion can cause new symptoms like heartburn, shortness of breath, and back pain as your body adjusts to your growing baby.

How Big is My Baby at 25 Weeks?

Your baby at 25 weeks is about the size of a rutabaga or a large eggplant, measuring approximately 13.6 inches (34.6 cm) from crown to heel.³

Weight-wise, your baby now weighs around 1.5 pounds (660 grams)—a significant increase from just a few weeks ago. From this point forward, your baby will gain weight rapidly, approximately 6 ounces per week.⁴

Despite this growth, your baby still has plenty of room to move around. The amniotic fluid provides cushioning and space for your baby to practice movements that will be essential after birth.

Baby Development at Week 25

Remarkable developments are happening this week:

Lung maturation continues: Your baby’s lungs are developing the air sacs (alveoli) and beginning to produce surfactant, a substance that helps the lungs expand and prevents them from collapsing. While the lungs aren’t mature enough for breathing air yet, this development is crucial for survival if early delivery occurs.⁵

Brain development accelerates: Your baby’s brain is growing rapidly, with billions of neurons developing and forming connections. The brain tissue is becoming more complex, with distinct regions for different functions beginning to specialize.⁶

Hearing is fully functional: By 25 weeks, your baby’s ears are fully developed and functional. They can hear your voice, your heartbeat, digestive sounds, and external noises. Studies show babies can recognize their mother’s voice at birth, suggesting they learn and remember sounds from the womb.⁷

Response to light: Your baby’s eyes are developing rapidly. While their eyelids are still fused shut, they can sense light through the uterine wall and may turn toward or away from bright lights shined on your belly.

Skin development: Your baby’s skin is still translucent and wrinkled but is gradually becoming more opaque as fat begins to accumulate underneath. You can still see blood vessels through the skin at this stage.

Blood vessels in lungs develop: Capillaries are forming in your baby’s lungs, preparing for the gas exchange that will be essential for breathing after birth.

Nostrils open: This week, your baby’s nostrils, which were previously plugged, begin to open. Your baby practices “breathing” movements by inhaling and exhaling small amounts of amniotic fluid, which helps lung development.⁸

Startle reflex develops: Your baby may startle in response to sudden loud noises, showing increasingly sophisticated neurological development.

Common Symptoms at 25 Weeks Pregnant

As your baby grows, you may experience new or intensifying symptoms:

Heartburn and indigestion: The hormone progesterone relaxes the valve between your stomach and esophagus, allowing stomach acid to creep upward. Your growing uterus also pushes on your stomach, exacerbating the issue.⁹

Hemorrhoids: Increased blood volume and pressure from your growing uterus can cause swollen veins in your rectum. Constipation can worsen hemorrhoids.

Back pain: Your growing belly shifts your center of gravity forward, straining your back muscles. The hormone relaxin also loosens ligaments in preparation for birth, which can contribute to discomfort.¹⁰

Leg cramps: Many pregnant people experience painful leg cramps, especially at night. The exact cause isn’t fully understood, but it may relate to changes in blood circulation or mineral levels.

Restless leg syndrome: An uncomfortable urge to move your legs, particularly when trying to sleep, affects some people during pregnancy.

Frequent urination: Your baby is pressing on your bladder, reducing its capacity and sending you to the bathroom more often.

Braxton Hicks contractions: You may begin feeling occasional, irregular tightening of your uterus. These “practice contractions” are normal and help prepare your body for labor.¹¹

Swelling (edema): Mild swelling in your feet, ankles, and hands is common as your body retains more fluid. Elevating your feet and staying hydrated can help.

Shortness of breath: Your growing uterus pushes up on your diaphragm, reducing lung capacity slightly. This improves after your baby “drops” into your pelvis closer to delivery.

When to Call Your Doctor

Contact your healthcare provider if you experience:

• Severe or sudden swelling, especially in your face and hands (possible preeclampsia)
• Severe headaches, vision changes, or upper abdominal pain
• Decreased fetal movement
• Signs of preterm labor: regular contractions, pelvic pressure, lower back pain, fluid leaking

Tips for Week 25

Prepare for the glucose screening test: Most providers schedule the glucose tolerance test between weeks 24-28 to screen for gestational diabetes. Ask your provider about any special instructions.¹²

Sleep on your left side: Sleeping on your left side optimizes blood flow to your baby and helps reduce swelling. Use pillows between your knees and under your belly for support.

Address heartburn: Eat smaller, more frequent meals; avoid spicy or acidic foods; don’t lie down immediately after eating; and keep your upper body elevated during sleep. Ask your provider about safe antacids if needed.

Stay active: Gentle exercise like walking, swimming, or prenatal yoga can help with back pain, improve circulation, and boost energy. Always get your provider’s approval before starting new exercise.

Stay hydrated: Drink 8-10 glasses of water daily. Proper hydration helps prevent urinary tract infections, reduces swelling, and supports increased blood volume.

Start thinking about childbirth classes: If you haven’t already, research and sign up for childbirth education classes. These typically start around week 28-30.

Practice pelvic floor exercises: Kegel exercises can help prevent incontinence and may aid in postpartum recovery. Tighten your pelvic floor muscles as if stopping urine flow, hold for 5-10 seconds, and release. Repeat 10-15 times, several times daily.¹³

Talk and sing to your baby: Since your baby can hear you, this is a wonderful time to bond through voice. Reading aloud or playing music can be soothing for both of you.

Plan for maternity leave: Start discussing maternity leave with your employer and understanding your rights under FMLA or other policies.

Third Trimester Preparation

With the third trimester approaching in just a few weeks, it’s a good time to start preparing:

Create a baby registry: If you haven’t already, start researching essential baby items and creating a registry for loved ones.

Tour your birth facility: Many hospitals and birth centers offer tours starting in the second trimester. This helps you know what to expect and where to go when labor begins.

Interview pediatricians: Start meeting with potential pediatricians so you can choose one before your baby arrives.

Consider creating a birth plan: Think about your preferences for labor and delivery—pain management, who you want present, newborn procedures—and discuss them with your provider.

Tracking Your Baby’s Growth with Nooko

At 25 weeks, you’re experiencing increasingly strong fetal movements and preparing for the final stretch of pregnancy. Nooko helps you track your baby’s kicks, log symptoms like heartburn or back pain, and stay organized with appointment reminders.

Use Nooko to document your baby’s movement patterns, share kick counts with your healthcare provider, and access evidence-based information tailored to week 25 of your pregnancy. Your journey is unique, and Nooko is here to support every step.

Download Nooko on the App Store | Get Nooko on Google Play

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References

Footnotes

1. Cleveland Clinic. (2025). “Fetal Development: Week-by-Week Stages of Pregnancy.” https://my.clevelandclinic.org/health/articles/7247-fetal-development-stages-of-growth ↩

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. BabyCenter. (2025). “25 Weeks Pregnant.” https://www.babycenter.com/pregnancy/week-by-week/25-weeks-pregnant ↩

4. Mayo Clinic. (2024). “Fetal development: The 2nd trimester.” Mayo Clinic Guide to a Healthy Pregnancy. ↩

5. Mayo Clinic. (2024). “Fetal development: The 2nd trimester.” https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/fetal-development/art-20046151 ↩

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

7. Kisilevsky BS, et al. (2003). “Fetal sensitivity to properties of maternal speech and language.” Infant Behavior and Development, 32(1), 59-71. ↩

8. Cleveland Clinic. (2025). “Fetal Development: Week-by-Week Stages of 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. Mayo Clinic. (2024). “Braxton Hicks contractions.” https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/expert-answers/braxton-hicks-contractions/faq-20057927 ↩

12. American College of Obstetricians and Gynecologists. (2025). “Gestational Diabetes.” https://www.acog.org/womens-health/faqs/gestational-diabetes ↩

13. American College of Obstetricians and Gynecologists. (2025). “Pelvic Floor Disorders.” https://www.acog.org/womens-health/faqs/pelvic-floor-disorders ↩