Pregnancy Week by Week
23 Weeks Pregnant
At 23 weeks pregnant, baby is the size of a large mango (~29 cm, 500 g). Lungs begin producing surfactant as the viability threshold approaches.
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This article is for general information and is not a substitute for professional medical advice. Always consult your pediatrician or doctor about your child.
Sources: WHO, CDC, AAP and NHS guidance. Recommendations differ between countries — for local advice see the NHS or ACOG.
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At a Glance: Week 23
- Trimester: Second trimester — approaching the viability threshold
- Baby's size: About the size of a large mango — roughly 29 cm (11.4 inches) crown to heel and approximately 500 g (17.6 oz)
- Key milestone: The lungs begin producing surfactant — the substance that will let air sacs stay open after birth. Blood vessels in the lungs are developing rapidly to prepare for breathing air. Hearing is fully functional, and your baby is becoming acquainted with the soundtrack of your daily life.
Your Baby's Development This Week
Week 23 marks the start of an enormously consequential stretch of fetal development. Lung maturation, fat deposition, and brain refinement all accelerate. Babies born at this gestational age can sometimes survive with maximal NICU support, although the road is hard. Each additional week of pregnancy meaningfully improves outcomes.
- Lungs: Type II pneumocytes start producing surfactant — the substance that prevents alveolar collapse on exhalation. Branching of the airways continues; pulmonary blood vessels multiply.
- Skin: Still red and wrinkled because subcutaneous fat is only just starting to accumulate. The skin is becoming less translucent as new cell layers form.
- Hearing: Fully functional. Your baby reliably perceives external sounds — voices, music, the dog barking — through the abdominal wall.
- Pancreas: Developing rapidly, beginning to produce insulin in response to glucose.
- Inner ear and balance: The vestibular system that controls balance is maturing. Your baby can sense your movement and position.
- Movement and reflexes: Kicks, rolls, and stretches are stronger. Startle, grasp, and sucking reflexes are practicing for life outside.
- Eyes: Still fused shut, but rapid eye movements during sleep cycles are beginning.
Your Body and Symptoms This Week
At 23 weeks the top of your uterus sits about 3 to 4 cm above the belly button. Your fundal height in centimeters should roughly match your weeks of pregnancy. Many people start to feel decisively "pregnant" — both in size and in symptoms.
- Braxton-Hicks contractions: Irregular, painless tightenings are common. They ease with rest, hydration, or changing position.
- Swelling (edema): Mild swelling in feet and ankles is common as blood volume peaks and the uterus presses on leg veins.
- Leg cramps: Often strike at night. Calf stretches before bed and adequate hydration can help.
- Growing belly: The bump may seem to expand quickly now. Skin stretching can cause itching, especially across the belly.
- Round-ligament pain: Brief, sharp pain in the lower abdomen or groin when you change position.
- Heartburn and indigestion: The growing uterus presses upward on the stomach. Small, frequent meals and avoiding lying down right after eating help.
- Snoring and nasal congestion: Pregnancy hormones swell nasal tissues; a humidifier and saline rinses can ease symptoms.
Nutrition: What to Eat and Avoid This Week
With the glucose tolerance test coming up at 24 to 28 weeks, week 23 is a good time to take a clear-eyed look at how you are eating carbohydrates. You don't need to restrict — just steady the swings.
Focus on:
- Lower-glycemic carbs: Whole grains (oats, brown rice, quinoa), beans, lentils, fruit with skin, and starchy vegetables in modest portions. Pair carbs with protein and fat to slow glucose spikes.
- Iron with vitamin C: Lean meat, lentils, or fortified cereal with citrus, peppers, or strawberries — the Institute of Medicine recommends about 27 mg of iron daily during pregnancy.
- Calcium-rich foods: Aim for about 1,000 mg daily from yogurt, cheese, fortified plant milks, calcium-set tofu, almonds, and leafy greens.
- Omega-3 DHA: 8 to 12 oz per week of low-mercury fish, or an algal DHA supplement, supports brain and eye development.
- Hydration: 2 to 2.5 L of fluids daily helps with constipation, swelling, and Braxton-Hicks.
Continue to avoid: alcohol, high-mercury fish (shark, swordfish, king mackerel, tilefish), raw or undercooked animal foods, unpasteurized dairy, and unheated deli meats. Keep caffeine under 200 mg/day per ACOG guidance. Sugary drinks (juice, soda, sweetened coffee) are a common driver of borderline glucose test results — consider swapping for water with citrus or unsweetened sparkling water.
Movement and Exercise
ACOG recommends about 150 minutes per week of moderate-intensity activity for uncomplicated pregnancies. Regular movement at 23 weeks lowers gestational diabetes risk, eases back pain, supports better sleep, and is associated with shorter labors and easier recovery.
Best choices this week: walking, swimming, stationary cycling, prenatal yoga, modified strength training, and daily pelvic floor exercises (Kegels — three sets of 10 daily).
Posture matters: the bump is pulling your center of gravity forward and increasing the lumbar curve. Engage your core gently when lifting, avoid arching the lower back, sit with both feet flat on the floor, and consider a maternity support band for long days on your feet.
Modify or avoid: exercises that involve lying flat on your back for more than a few minutes (use an incline), holding your breath against resistance, deep twists, contact sports, hot yoga, and any activity with a meaningful fall risk. Stop and rest if you feel dizzy, breathless, cramping, or notice bleeding or fluid loss.
Mental and Emotional Wellbeing
Reaching the edge of viability is emotionally complicated. Many parents describe a new layer of awareness around now — gratitude for how far things have come, mixed with fresh anxiety about what could still go wrong. Both reactions are normal.
Sleep: Often worsens. Side sleeping with a pillow between the knees and one supporting the bump can help. If you wake on your back, simply roll to your side — there is no harm in occasional shifts.
Mood check: Prenatal depression and anxiety affect roughly 1 in 5 pregnant people and are treatable. Talk to your provider if you feel persistently down, lose interest in usual activities, or worry constantly. Many evidence-based treatments — therapy, peer support, sometimes medication — are safe in pregnancy.
Partner involvement: External kicks are often easier for a hand on the belly to feel between 22 and 26 weeks. This shared moment can deepen bonding meaningfully.
Common Concerns and When to Call Your Doctor
Contact your provider promptly if you experience:
- Vaginal bleeding (any amount)
- Sudden gush or persistent leak of fluid
- Severe or persistent abdominal pain
- Regular tightening (more than 4 per hour) — possible preterm labor
- Pelvic pressure, low-back ache in waves, or menstrual-like cramping
- Severe headache, vision changes, sudden swelling of hands and face, or upper-abdominal pain (preeclampsia red flags)
- Painful urination, lower-back pain with fever (possible UTI or kidney infection)
- One-sided leg swelling, pain, or redness (possible blood clot)
- A meaningful drop in movement once you have established a consistent daily pattern
Tests and Appointments This Week
You'll likely have a routine prenatal visit around now with weight, blood pressure, urine dip, fundal height, and Doppler check of the fetal heartbeat. Your provider may schedule the upcoming glucose tolerance test (typically between 24 and 28 weeks) and review preterm-labor warning signs as you cross into the viability window. If you have a short cervix history or other risk factors, a cervical length scan may be ordered. Some practices offer a brief "viability discussion" at this visit — what would happen if labor started now, what NICU support looks like, and what tools (like betamethasone, the steroid that accelerates lung maturity) might be used.
Tips for Week 23
- Prep for the glucose test. In the days leading up, focus on steady carb intake — whole grains, beans, fruit — and stay well hydrated. Avoid loading up on sugar the night before.
- Memorize preterm-labor warning signs. Save your provider's after-hours number where you can find it quickly.
- Start gentle calf stretches at bedtime. Two minutes of stretching often prevents the worst of nighttime leg cramps.
- Book a childbirth class. Six to twelve weeks in advance is typical.
- Talk to your baby. Hearing is fully functional; voices heard now help with newborn voice recognition.
Preparing for What's Next
The third trimester begins at 28 weeks — only five weeks away. Now is the time to start practical preparation: research pediatricians, draft a baby registry, plan parental leave with your employer, and look into childbirth and breastfeeding classes. Begin gathering hospital-bag essentials a little at a time so you are not assembling it in a rush late in the third trimester. Consider drafting a first version of your birth preferences as a way to clarify what matters to you and open conversations with your provider.
Frequently Asked Questions About Week 23
What does "viability" actually mean and where does 23 weeks fit in?
Viability refers to the gestational age at which a baby has a reasonable chance of surviving outside the womb with intensive medical support. In modern, well-resourced NICUs, the threshold is typically described as 22 to 24 weeks, with survival rates climbing sharply each additional week. At 23 weeks, survival with active resuscitation is possible but still limited, and the risk of significant long-term complications is high. By 24 weeks, survival rates and outcomes improve meaningfully. These conversations are always individualized — your obstetric and neonatal team will discuss specifics based on your situation.
What is surfactant and why does it matter so much right now?
Surfactant is a soapy substance produced by specialized cells in the developing lungs (type II pneumocytes). It coats the inside of the air sacs (alveoli) and keeps them from collapsing on exhalation. Without enough surfactant, a premature baby cannot effectively inflate their lungs to breathe air. Surfactant production starts modestly around 23 to 24 weeks and ramps up substantially through the third trimester. This is one of the biggest reasons each additional week of pregnancy meaningfully improves outcomes for a baby born preterm.
How often should I be feeling my baby move at 23 weeks?
Most pregnancies establish a clearer daily pattern of activity between weeks 24 and 28. At 23 weeks, movements are becoming more consistent — many parents notice quiet stretches and active stretches — but counting is not yet formally recommended. Babies still sleep in 20- to 40-minute cycles, and placenta position affects how much you feel. Focus on noticing patterns rather than counting. Call your provider if you have established a clear pattern and notice a meaningful decrease.
Why are my feet and ankles starting to swell at 23 weeks?
Blood volume during pregnancy increases about 50% above baseline, and the growing uterus presses on veins returning blood from the legs. Both effects produce mild swelling (edema) in the feet, ankles, and sometimes hands — especially by the end of the day, in warm weather, or after long standing. Elevate your feet, stay hydrated, and move regularly. Call your provider if swelling is sudden, severe, asymmetric (one leg only), or accompanied by headache, vision changes, or upper-abdominal pain — those can be signs of preeclampsia or a blood clot.
What is the glucose tolerance test like?
The screening test typically scheduled between 24 and 28 weeks involves drinking a sweet glucose solution (50 g) and having your blood drawn an hour later. You don't have to fast for the screening. If the result is elevated, a longer diagnostic test follows: a fasting blood draw, then a 100 g glucose drink with blood draws at 1, 2, and 3 hours. Most people pass the screening. If diagnosed with gestational diabetes, treatment with diet, monitoring, and sometimes insulin is highly effective.
Is it safe to fly at 23 weeks pregnant?
Most airlines and obstetricians consider air travel safe for uncomplicated pregnancies through about 36 weeks for domestic flights and 32 to 35 weeks for international flights (policies vary). At 23 weeks, you are in a comfortable window for travel. Walk the aisle every hour, stay well hydrated, wear compression stockings to reduce clot risk, and ask your provider whether your specific situation has any restrictions (e.g., placenta previa, preterm labor history).
How can I tell the difference between Braxton-Hicks and real contractions?
Braxton-Hicks contractions are irregular, painless or mildly uncomfortable, don't intensify over time, and ease with rest, hydration, or changing position. True preterm labor contractions are regular, become more frequent over time (more than 4 per hour), grow stronger and longer, do not ease with rest, and often come with low-back pain, pelvic pressure, increased or watery discharge, or any bleeding. Call your provider immediately if you suspect preterm labor — early evaluation matters at this gestational age.
Why am I waking up with leg cramps now?
Nighttime leg cramps are very common in the second and third trimesters. The cause is not fully understood — pressure on nerves from the growing uterus, circulation changes, and shifts in calcium, magnesium, and potassium balance all probably contribute. Gentle calf stretches before bed, adequate hydration, comfortable shoes during the day, and dietary calcium and magnesium often help. When a cramp strikes, flex your foot upward toward your knee and massage the calf.
Is it normal to be more emotional or anxious this week?
Yes. Reaching the viability threshold often brings a wave of complicated emotions — relief, gratitude, but also new awareness of what could go wrong. Hormonal shifts, sleep disruption, and the sheer weight of "this is real" all contribute. Talk to your partner, friends, or a therapist. Reach out to your provider if you feel persistently down or anxious, lose interest in usual activities, or have intrusive thoughts. Prenatal anxiety and depression affect roughly 1 in 5 pregnancies and respond well to treatment.
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