GUIDE

23 Weeks Pregnant

Published on ·Updated on

Your baby can now hear external sounds clearly, and their lungs are developing surfactant — a critical substance for breathing.

At the size of a grapefruit, your baby is approaching the viability milestone, and every day of development matters.

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Baby's Development at Week 23

Your baby is about the size of a grapefruit — roughly 11.5 inches long and weighing just over 1 pound. This week marks important advances in both hearing and lung development.

Your baby can now hear external sounds clearly. While internal sounds — your heartbeat, breathing, and digestion — have been audible for weeks, your baby can now pick up voices, music, and environmental noises from outside your body. Loud or sudden sounds may startle them, and you might feel a kick in response. Research suggests that babies begin developing preferences for sounds and music they hear frequently in the womb.

The lungs are reaching a critical stage of development. Cells in the lungs are beginning to produce surfactant, a complex substance that coats the inside of the air sacs (alveoli) and prevents them from collapsing with each breath. Without adequate surfactant, breathing is extremely difficult. The lungs are not yet mature enough to function independently, but this early surfactant production is a vital step toward eventual viability.

Blood vessels in the lungs are also developing, preparing for the moment when they will need to exchange oxygen and carbon dioxide with the air. Your baby continues to practice breathing movements by inhaling and exhaling amniotic fluid — these rhythmic chest movements help the lungs and diaphragm develop.

Since last week, your baby's sense of touch continues to refine, and the face looks increasingly like the baby you will meet at birth.

Your Body This Week

At 23 weeks, your uterus extends about an inch above your belly button, and you may feel like your belly has grown noticeably in just the past few days. The growth is rapid now, and your body is adjusting in multiple ways.

Swollen feet and ankles are becoming more common as your uterus puts increasing pressure on the veins returning blood from your lower body. Gravity does the rest — fluid pools in your feet and ankles, especially if you have been standing or sitting in one position for a long time. Elevating your feet, rotating your ankles, staying hydrated, and wearing comfortable shoes without restrictive seams can all help. Sudden or severe swelling, especially in your face or hands, is a different story — call your provider.

Braxton Hicks contractions may be happening more frequently. They are still practice contractions and should remain irregular and painless. If they start coming at regular intervals or are accompanied by pain, pelvic pressure, or any fluid leakage, contact your provider right away.

"Pregnancy brain" — forgetfulness, losing your train of thought, misplacing things — is real and common. Research suggests that the brain actually undergoes structural changes during pregnancy that may affect short-term memory and focus. It is temporary and has nothing to do with intelligence. Give yourself grace, and lean on lists and reminders.

Common Symptoms at Week 23

  • More pronounced fetal movement — baby may respond to sounds, music, or your voice
  • Braxton Hicks contractions occurring more frequently
  • Swollen feet and ankles, especially in warm weather or after standing
  • Leg cramps, often at night, that can wake you from sleep
  • Gum sensitivity or bleeding when brushing teeth
  • Forgetfulness or difficulty concentrating — sometimes called pregnancy brain
  • Shortness of breath from your uterus pushing on your diaphragm

Every pregnancy is different. New symptoms may appear while others ease up — your body is constantly adapting.

What to Do This Week

This week brings both bonding opportunities and practical planning. Take advantage of your remaining second trimester energy.

Talk and read to your baby

Your baby can hear external sounds clearly now. Reading aloud, talking about your day, or playing music are all ways to bond and stimulate auditory development. Your baby will recognize your voice at birth, and this familiarity begins now.

Stretch before bed to prevent leg cramps

Calf stretches before you get into bed can reduce the frequency of nighttime leg cramps. Stand facing a wall with one foot behind you, heel on the ground, and lean forward gently. Hold for 30 seconds on each side. If a cramp strikes, flex your foot (toes toward your shin) to help it release.

Start thinking about pediatrician selection

It is not too early to research pediatricians. Ask friends for recommendations, check which providers are in your insurance network, and consider scheduling meet-and-greet appointments. Many pediatric practices welcome expectant parents for a brief visit to see if the practice is a good fit.

Review your workplace parental leave policy

If you have not already, get the details on your company's parental leave policy — how much time, paid versus unpaid, and any paperwork deadlines. If you plan to take FMLA leave, some employers require 30 days advance notice.

When to Call Your Doctor

  • Regular contractions — more than four per hour, especially if painful
  • Vaginal bleeding, spotting, or watery fluid leaking
  • Pelvic pressure that feels like the baby is pushing down
  • Sudden or severe swelling in your face, hands, or legs
  • Decreased fetal movement or a noticeable change in your baby's activity pattern

When in doubt, call your provider. Signs of preterm labor — regular contractions, pelvic pressure, fluid leaking — require prompt evaluation.

Looking Ahead

Week 24 is a major milestone — the viability threshold. Your baby will be the size of an ear of corn, and this is typically when the glucose screening test for gestational diabetes is done.

If you are dealing with heartburn or back pain, know that these symptoms often persist through the third trimester — but there are effective management strategies.

Related Guides

Sources

  • American College of Obstetricians and Gynecologists (ACOG) — How your fetus grows during pregnancy
  • Mayo Clinic — Fetal development week by week
  • National Institutes of Health (NIH) — Fetal development milestones
  • March of Dimes — Pregnancy week by week

This guide is for informational purposes only and is not a substitute for professional medical advice. Always consult your healthcare provider with any questions about your pregnancy.

Frequently asked questions

What is surfactant and why does it matter?
Surfactant is a substance produced by the lungs that keeps the air sacs (alveoli) from collapsing when you exhale. Without enough surfactant, a baby's lungs cannot function properly outside the womb. Production begins around 23-24 weeks and continues to increase until birth. This is one reason why premature babies often have breathing difficulties — their lungs may not have produced enough surfactant yet.
What does viability mean at 23 weeks?
Viability refers to the point at which a baby has a chance of surviving outside the womb with intensive medical care. At 23 weeks, survival is possible but outcomes vary significantly depending on the medical facility and individual circumstances. Each additional week of development dramatically improves survival rates and reduces complications.
Can my baby recognize my voice at 23 weeks?
Your baby can hear your voice clearly and is beginning to recognize it. Studies show that newborns prefer their mother's voice immediately after birth, which suggests they have been learning it in the womb. Your voice reaches your baby both through the air and through vibrations in your body, making it the loudest and most familiar sound.
Why do I get leg cramps at night during pregnancy?
Nighttime leg cramps are common in the second and third trimesters. The exact cause is unclear, but it may be related to changes in circulation, pressure on nerves from your growing uterus, fatigue in your leg muscles from carrying extra weight, or mineral imbalances. Stretching your calves before bed, staying hydrated, and eating potassium-rich foods (like bananas) can help.
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